Theresa Cassidy was born to Sean Cassidy , the first Banshee, and Maeve Rourke while Sean was away on a mission for INTERPOL. Not long after Theresa's birth, Maeve was killed by a bomb blast and young Theresa was taken in and cared for by her uncle, Thomas Cassidy , a.k.a. Black Tom. When Sean finally returned home from his mission to find Maeve dead, he directed his anger toward his brother Tom for not looking after her, attacking him and breaking his leg. Out of spite, Tom never told Sean about his daughter, allowing Sean to believe that Theresa had died with her mother.Tom decided to raise his niece on his own. As time went by, Tom became involved in increasingly dangerous criminal activities and, for her protection, shipped the twelve-year-old Theresa off to St. Elizabeth's Boarding School. When she was fifteen, she found out that Black Tom had been arrested by INTERPOL agents. After Theresa developed her mutant abilities--a sonic scream, the same as her true father's--she joined her uncle in his life of crime under the moniker Siryn. She would eventually discover the truth of her origin, however, and become a hero.
Siryn was created by writer Chris Claremont and artist Steve Leialoha.
Beginning as a criminal, Siryn would join the mutants on Muir Island and then X-Force, as deputy leader.
Major Story Arcs
Siryn first joined her uncle Black Tom, as well as Juggernaut, in order to learn the tricks of the villain trade. Their first mark is a bank in San Francisco that was holding a rare and expensive metal called vibranium. In fact, it was scheduled for pick-up the next day by Nick Fury. Tom asked Siryn if she was nervous and she replied that she was a bit, but insists that she won't let him down. Professor Xavier, sensing Siryn’s presence, sent the X-Men to investigate the young mutant. As the robbery of the bank began, Siryn’s use of her powers alerted Spider-Woman . Spider-Woman entered the mint to find a trail of destruction from Siryn, which included broken walls and unconscious people. Spider-Woman eventually caught up to Siryn and the two battled. Despite being an untested teenager, Siryn showed incredible control of her powers. Regardless, Spider-Woman was able to knock Siryn out with a venom blast, but was disabled by Juggernaut before being able to detain the other villains. Spider-Woman joined with the X-Men and they pursued the cabal of thieves to a ship. After a prolonged fight, the villains were defeated. Siryn had been hit with another venom blast and was being loaded into an ambulance when an arrested Black Tom submitted to allowing Siryn to enter the care of the X-Men as an alternative to prison. Not long after, Siryn was united with her true father, Sean Cassidy in Xavier’s Mansion.
Theresa next moves to Muir Island with her father, Moira MacTaggert , and Jamie Madrox. During an overnight visit to Xavier Institute, Siryn, Kitty Pryde , Illyana Rasputin, and Amp battle robotic duplicates of the Brotherhood of Evil Mutants after accidentally releasing them from the Danger Room. On another visit to America, Siryn is able to join Dazzler on stage as both a back-up singer and bodyguard. When danger is suspected, Siryn uses her sonic abilities to amplify Dazzler's to make a bright light display, blinding the audience while Wolverine sorts out any trouble. While living back on the island, Siryn starts a romantic relationship with the supposed Jamie Madrox. Soon after, Siryn and Multiple Man travel to New York City at the request of Magneto, the head of Xavier's Institute for Higher Learning at the time. She and Madrox begin a search to help the New Mutants find two of their members, Sunspot and Warlock, who have run away from the school. Theresa and Jaime find Sunspot and meet the association of street-level mutants known as the Fallen Angels. They are unsuccessful in convincing the boys to return with them and feel forced to stay and help out as best as they can. The Fallen Angels are transported to Devil Dinosaur's planet. They then travel to the Coconut Grove, the home planet of the alien Ariel. While there, her superhuman powers are neutralized and she is made a captive by a being named Unipar. She regains her superhuman powers and freedom and returns to Earth. She decides to remain in the Fallen Angels for a time to help reform their criminal members.
Later, back on Muir Island, she fell under the mental control of the Shadow King. Thankfully it didn't take long until she was freed from the Shadow King's control.
Siryn would later become a founding member of X-Force, and for a time was its leader. As a member of X-Force, her teammate Warpath developed a romantic interest in her while Siryn began an on-going flirtation with the mercenary Deadpool. Deadpool and Siryn initially became involved when the two met while fighting her uncle and Juggernaut. Though Banshee warned Siryn that Deadpool was a madman and a murderer, she found herself quite taken with him, even looking past his horrific appearance. Due to this kindness, Deadpool became infatuated with Siryn to the point of obsession, and often sat outside her window as she slept in the X-Mansion.
Over time, Siryn became the voice of reason and sanity in Deadpool's ear, attempting to sway him to the side of good. She assisted him in some of his missions, such as when Deadpool felt he needed some blood from the Hulk in order to cure problems with his own healing powers. In the end, however, Siryn became overwhelmed with balancing her duties with X-Force and the demands of Deadpool's somewhat faulty sanity. She promised him that she would consider progressing their relationship if he continued on the path of good, and once she had her X-Force responsibilities secured. Meanwhile, Warpath continued to pursue Siryn's affections, making his dislike for Deadpool clear.
Siryn confronted varied adversaries during her time in X-Force. She helps put down a variety of enemies, such as Onslaught and Mojo. She even battled S.H.I.E.L.D. forces on more than one occasion. She also confronted more down to earth problems, particularly alcoholism, which she had struggled with from a young age, even during her time at St. Elizabeth's. Warpath helped her to cope with her drinking problem, and she began leading a sober lifestyle.
She left when Feral, a former teammate turned villain, slashed her throat, destroying her vocal cords and rendering her temporarily mute and powerless.
Thanks to the aid of Deadpool, Siryn was able to fully heal from her vocal cord injuries. Deadpool had tracked down Wolverine and stole a sample of his blood to heal her. Siryn then joined the Paris branch of the international mutant X-Corporation, where she reunited with old friends such as Multiple Man, Rictor, and Cannonball, and was first introduced to M.
Their first mission, helping the X-Men to hold off people under Huntsman's mind control, did not go well and Siryn has to deal with the loss of another friend, Darkstar. Siryn left the X-Corporation when it was closed.
Siryn later joined X-Factor: Investigations, formed by her former lover, Jamie Madrox.
When she first joined, Siryn was obtaining information from a woman named Victoria. Victoria had fallen "in love" with Siryn, but this was just because of Siryn's new-found power, the ability to use her vocal cords to persuade anyone (bar mutants) to fall in love with her and be suggestible to anything she said. Siryn used this ability on Victoria to get information on Mr. Manetta, a man who made mutants lives miserable. Victoria was eventually gunned down in front of Siryn and died in her arms. Siryn initially blamed Strong Guy for her death, as he was supposed to be back up. In pursuit of the gunmen, Siryn screamed at their car and knocked it over, throwing out the woman who fired the shots into the bar where Theresa had met Victoria. Enraged, Siryn shouted at the woman to shoot at her, but she instead chose suicide.
Back at base, Siryn is just staring at bottle of alcohol, as Layla Miller enters. Layla asks if she's going to drink it, but Siryn explains that she used to be an alcoholic and just intends on staring at it.
As Strong Guy and Siryn talk over Layla, Layla drops in quickly that the woman who shot Victoria was "an operative for a Detective Agency called 'Singularity Investigations,' a kind of a security outfit for the rich and famous." Siryn does intend on storming into Singularity, but Layla tells her that that isn't a good idea, and she should take the client who's about to enter the case (we see that Singularity had been expecting Siryn, but because a new force of chaos had been been introduced, her destiny had changed). Siryn takes the client's case, Gloria Santiago, who believes that her sister is being mind-controlled because she's been acting differently recently. Siryn goes to spy on Gloria's sister, and finds out that it's not mind-control, but actually that she'd been sleeping with actress Jack Vaughn.
We see Siryn talking in her sleep about Ewan McGregor and lightsaber and about venturing down the toilet with him, and when she's woken up, she finds out that Gloria Santiago has been arrested for the murder of her sister.
Siryn flies Jamie over to the crime seen, and uses her persuasion power to get past a police officer. She is about to make Jack Vaughn confess to what really happened with this power too, but is stopped by Damian Tryp. The two then fly down to the police, to try and get the truth from Gloria, but she is in so much shock, she can't remember anything. Siryn then leaves when M arrives to read Gloria's mind to find out the truth, so Siryn flies back to Mutant Town to help out with the invading authority trying to stop the riots in Mutant Town. Strong Guy and Wolfsbane managed to hold them off, but Siryn delivered the final blow and sent the authorities away with a scream.
Siryn offers Rictor to come and eat with her (after they get back to HQ), but he refuses. On the way to the cafe, Siryn is brutally attacked by Jr. (because X-Factor humiliated the firm), and left to die in an alley. She is then taken in by a crazy ex-mutant doctor, who treats her injuries. She was hit in the neck with a drug that rendered her unable to speak or scream (that's why she couldn't retaliate), so she couldn't escape from the doctor's bonds, who kept her gagged and bound. Luckily, Rictor re-accepted Siryn's offer of breakfast, and decided to follow her. He arrives at the theater where she's being held captive, and just as the crazy ex-mutant is about to attack him, Siryn breaks free and takes a single shot, pushing the ex-mutant, given Rictor a chance to kill him. She is then carried back to HQ by Rictor.
Siryn spends the next issue in bed, resting an recovering from her injury. A proper doctor comes to check out her injuries, revealing that it was a planned attack and the attacker knew where to hit to hurt her without killing her.
As Siryn recovers, she is visited by Cyclops , and receives the news that her father's dead. Siryn doesn't even re-act to this, and enters a state of denial, believing her father is just hiding to fool the enemies, and thinks he's still alive and says she isn't going to spend her time being upset only to have him waltz back into her life. Siryn watches the video her father left for her, explaining that she know owns Cassidy Keep. He also leaves her his special pipe, that he was given by his father; her grandfather.
Madrox gave Siryn the mission of tracking down major superheroes to try and find the truth about the Decimation . She tracks down Spider-Man, and after helping him take down a crook, uses her persuasion to get him to tell her everything about the Decimation, and when she finds out, she's not happy at all. She thinks that they should go to the Institute and demand the truth, but then the X-Men show up in Mutant Town, demanding Quicksilver, but X-Factor show up themselves to defend him. Colossus makes a tiny gesture and Siryn sonic lances him, knocking him back. After a convincing speech by Jamie, the X-Men then leave.
After Jamie gets drunk, he releases his libido dupe, and one sleeps with M and one sleeps with Siryn. When the team attack Singularity Investigations, Siryn goes with Rictor to get the information on what Singularity was doing. The group then go to see Doc Samson for a therapy session, we see that Siryn is still in denial about her father's death, and is quite happy about getting back together with Jamie. When Siryn finds out about the love triangle, she gives Jamie the silent treatment, because she believes that if she starts speaking she will then start screaming and destroy the whole city block.
Layla later forces M and Siryn to be friends, because they're not talking because of the love triangle. M suggests a shopping trip to Paris, which Siryn accepts, and the two fly out. The two eat in a restaurant while talking, and hear a noise from outside. They run out to see a riot, burning down a mutant hostel, filled with depowered mutants. Siryn and M defend it, but when the police turn up, they decide to go peacefully instead of being felons. In prison, a man walks by who had just been arrested, and boasts about how the gang of rioters went back to the hostel after the police left, and burned the police to the ground.After M crucified the man, the two broke out of jail and returned to the hostel, to find that the man was right, and it had been burned to the ground. Outside, they see the girl from the hostel window they saw the night before. She tells them her name is Nicole, and after a short discussion, M decides to take her home, despite Siryn being against the idea. They fly back in M's private jet, the same way they got there, but now as friends.
Messiah Complex & Pregnancy
During Messiah Complex, Siryn answers the call of Peepers who phones X-Factor believing he's being followed. When she finally arrives at the road he was driving on, she find his car to be off the road, crashed, and Peepers body mauled. She then prays over Jamie's unconscious body, praying for him to wake up, which he does. She then takes part in the final battle on Muir Island.
This arc begins with Siryn in a confessional booth, confessing about how been using the Lords name in vain, being jealous of M's iPhone and how she's been having impure thoughts about Jamie. She then revealed that she is also pregnant, and it's Jamie's baby.
We then see Siryn and M talking about her pregnancy, and M suggests an abortion, but Siryn quickly dismisses the idea. M also says she's Siryn's best friend now since Wolfsbane is gone.
Next, Siryn tries to tell Jamie she's pregnant, but he jumps to the wrong conclusion and believes she's leaving. M says that Siryn would have realized this if she wasn't in love with him. She tries to tell him again but he's called away by Strong Guy. When M hears Rictor calling, Siryn flies after her with a Madrox dupe.
After M is taken down, Siryn arrives on the scene as Rictor manages to save himself from castration. Siryn then saves Rictor when he's nearly run over by Arcade's cars and manages to figure that the place where the robot was receiving it's commands was close (well, M did the work before that, but...). Anyway, the team barge in to find the dying Purifier who recruited Rictor (during Messiah Complex), telling X-Factor that when he dies, so does Mutant Town.
The team then go and patrol the streets, saving innocents, Siryn saves a terrible comedian (an ex-mutant), who constantly tries to make Siryn laugh with terrible jokes. After the trouble ends, the group head back to base, where Guido, M and Siryn rest their feet as they listen to a Daniel Day song ("Bad Day"). Jamie brings in Val Cooper, who gives the team an option of being put into the witness protection program or working for the government. She gives them twenty-four hours to decide. The team goes to see Jamie who went to the hospital to visit the man, Nathan, who he helped earlier. After finding out he died, Jamie asks Siryn can they name the baby Nathan after him, and as she goes to say it reminds her of someone (most probably Cable), she stops mid-sentence asking him how he knows (his conscious, as Layla, told him, telling him he had been noticing the signs), and then the whole team finds out. The team then walks home happily together, and leave a pre-recorded message for Val Cooper, and blew up the building. Five months later in Detroit, a depowered mutant comes to the door looking for "XF Investigations", thinking she's going to be killed, and a heavily pregnant Siryn answers the door, telling Guido to ring Jamie.
When Siryn's water breaks she's involved in a siege of her home by government agents lead by Val Cooper who is shot during Rictor's attempt to save Siryn and the unborn baby under the impression the government have a vested interest in kidnapping the unborn baby.
Madrox and the rest of the team meet Siryn at the hospital and Jamie surprisingly doesn't miss the birth of his child, he even takes lengthy safety precautions to ensure his baby isn't abducted utilizing his team members and dupes to watch over the baby and Siryn. She decides that she wants to name the baby after her late father Sean and the baby is named accordingly but then, on holding baby Sean for the first time something unexpected happens. Now mutant births are notoriously different and unpredictable but baby Sean starts to glow, then in Madrox's hands he is absorbed not dissimilar to one of his ordinary dupes. It is then apparent that on the night of conception it was in fact a dupe which knocked Siryn up and not Jamie. Siryn attempts to claw baby Sean from within Jamie's chest but is unsuccessful, the episode ends with Siryn breaking Jamie's finger and promising to break his neck.
Theresa went back home across the Atlantic Ocean after her time in charge of X-factor Investigation. In her grief, she re-unites and sleeps with Deadpool.
Honoring her father's name
In the graveyard of Cassidy Keep in Ireland, Theresa Cassidy speaks to her departed father at his mausoleum, despite the fact that his body is buried across the Atlantic in the States. Promising to bring him home to where he should truly rest, she begins to break down until she’s offered a handkerchief by a priest. Her sorrow turns to anger when she sees that it seems to be Jamie Madrox and she lashes out. However, she quickly realizes that he’s actually a dupe who went rogue after becoming a reverend. Much against Theresa’s intention to do so, the two discuss God and any plan that He might have for people and the reason for allowing such sorrow in their lives. Their conversation is interrupted by a gunshot, which leads to two poaching hunters. One having shot a fawn, rather than its mother, the two run off at hearing Theresa’s sonic scream, believing her to be a banshee.
Arriving at the scene together, Father Maddox and Theresa see the slain fawn and its mother, which refuses to leave its young. Sitting on a nearby log, they continue their discussion, which includes Theresa’s decision to take her father’s name of “Banshee.” Finally, Father Maddox manages to bring Theresa some peace, using the doe’s perception of her fawn’s death, its meaning and what it will take for her to get over it. During the Asgard Case at Las Vegas, Theresa took time prior to the Battle with Hela and the Norse Zombie Warriors to let Jaime know that she had accepted what happened to them in relationship with their baby. She does not blame him anymore and that she was sorry for breaking his finger.
Juggernaut is granted tremendous power by the Asgardian Serpent, and he is now heading toward San Francisco. The X-Men engage him. After the X-Men find out all their attacks are proving useless, Cyclops has a lot of the X-Men attack in pairs / combos that would seem otherwise very powerful against any other foe. Cyclops has Pixie teleport Siryn in and combines her with Dazzler for Plan 33. Siryn's sound energy synergizes with Dazzler's sound-to-light power to generate extremely intense lasers. This plan resulted in being ineffective.
Theresa left X-Factor in the Breaking Points story arc. She had a couple of battles with the Celtic Goddess of War and Death, the Morrigan. Theresa first encountered The Morrigan when Theresa was trying to solve a series of murders in company of Havok in upstate New York. During the final battle, The Morrigan did not allow Banshee to use her sonic powers. Theresa barely escaped this first encounter by attacking a crow that was with the Morrigan after Jezebel suggested it. The crow had some kind of connection to the Morrigan´s powers. Soon after that, Theresa began to have visions of her dead father. She did not understand why that was happening to her. She thought she was going insane. She even could talk to her dead father, Banshee. Previously in the Breaking Points Day 3, Polaris went crazy after she discovered the truth about the way how her parents died. Theresa wanted to help Polaris but the only way to save her life was to face the Morrigan one more time. She reached for help from Layla Miller to invoke the goddess because she felt that it could help her and her friend. It was something she had to do.
It turned out, that the first encounter was a test for Theresa because the Morrigan did not want to kill her but to swap roles with her. She wanted Therese to assume her identity to continue with her tasks and duties for good. The Morrigan felt that her time had already come up. She was choosing someone to replace her and she thought that Theresa was the right candidate for the job. In order to save Polaris, Theresa had to accept her new role as the Morrigan but the price and stakes to pay for it were too high. Theresa did not even hesitate in accepting her new role. After she grabed the Morrigan´s hand in acceptance, Theresa became the Goddess of War and Death. She screamed and Polaris came up from her deeply sleep to be normal again. After that Theresa could not stay with the team. It´s not clear if she died in order to become a Godless of War and Death. Later, she visited Madrox one more time to say good bye and to confesses to him that she was still in love with him before she vanished. She suggested to him to pray to her if he ever needed help in the future. After that, she vanished
After the Hell On Earth War, Madrox was transformed into a nearly mindless demon. Layla, now his wife, took care of him on the old Madrox family farm, but his mind deteriorated daily. One day, Layla discovered that she was pregnant with Madrox's child, and he seemed to understand this. Tryp brought the cops to the farm to arrest them for squating, but Madrox prayed to Theresa, who returned him to his natural state. Now safe from Tryp's plan, Madrox told Theresa that he and Layla were retiring from X-Factor.
Powers and Abilities
Siryn has sonic powers as a result of her mutation, like her father, but has displayed abilities he hasn't. Siryn can create a sonic scream, and these screams are powerful enough to shatter glass, knock people out and apparently, destroy a city block. Siryn can also channel her scream into a "sonic lance", where she screams a tightly focused sound vibration, and can use it to cause incredible pain, inflict damage, stun people or shatter objects.
Like the Siren's of myth, Siryn can use her voice to make people fall in love with her and, in this state, they are susceptible to anything she orates. Mutants are immune to this power, but other superhumans aren't, like when she used her power to make Spider-Man tell her everything about the Decimation, per Madrox's orders. It doesn't matter what gender the person she uses her seduction powers on.
Siryn is able to manipulate sound waves to propel herself through the air, gliding with ease and maneuvering by inflating sound pockets with which to bounce off of.
Siryn can also use her powers to enhance her hearing, use it as a radar sense of sorts, create force fields, stop current sounds from reaching others and talk so only one person can here (her powers are more like Sonokinesis than just sonic powers, but that is how they're described).
Siryn is immune to all of her powers.
Age of Apocalypse - Earth-295
Siryn of the Age of Apocalypse universe is called Sonique. Theresa’s counterpart from the Age of Apocalypse apparently never learned who her father was. In fact, she was living in an unnamed town in Kansas that was one day attacked by Apocalypse’s forces. All of the townsfolk were captured and shipped off to a testing facility to test them for mutant genes. However, Forge’s Outcasts of mutants attacked the transport to free the prisoners. When Theresa tried to warn one of Forge’s friends, Nate Grey, that he was about to be attacked from behind, she manifested her sonic scream for the first time.
Joining the group as well, she adopted the moniker Sonique. Theresa and Nate quickly fell in love, but destiny had a much bigger fate for Nate in store. With both Apocalypse’s assassins and Sinister coming after him, killing Forge’s group one by one, he eventually left to face Apocalypse all by himself, leaving Sonique in the care of their sole surviving teammate, Soaron. Later on, they were both brainwashed to serve among Sinister’s Six, but after being defeated by the X-Men, the tampering with Theresa's mind could be undone.
X-Men The End (Earth-41001)
Siryn and Multiple Man ended up sharing the same fate, though it was an unpleasant one. Both of them had, at some point, been captured by Tullamore Voge and his slavers, who had turned them into Hounds. Apparently their former teammates were unable to rescue Jamie and Theresa from the slavers, either because they didn’t know of their fate or because they didn’t know where they were being held. Not to mention that with numerous of their arch-enemies working together to orchestrate The End of the X-Men, the followers of Xavier’s dream were too busy fighting for their very lives to even consider a rescue mission with unlikely chances of succeeding.
In Other Media
X2: X-Men United
She is played by Shauna Kain. Her physical manifestation and her powers have stayed the same from what we have seen.
Siryn is one of the children captured by William Stryker's men. Though she was tranquilized, she managed to wake up the entire school so they could escape. Her name (along with her father's) also appears on a list of names Mystique scrolls through on Stryker's computer while looking for Magneto's file.
In the novelization for the film (written by Chris Claremont), Siryn and a young Jamie Madrox are involved in a budding teen romance.
X-Men: The Last Stand
In The Last Stand, she can be seen in the scene where Professor X is teaching his class.
Then later mourning, we can see her again in Charles Xavier death, with the rest of the X-Men and others Xavier's friends.
X-men: Battle of the Atom
Siryn is feattured in the mobile card game X-men: Battle of the Atom. Her Cards are:
- Siryn is the 159th character released in Marvel Classic Figurine Collection.
- Siryn has two variants in the heroclix game: One with her original X-Factor costume (As part of the Giant Size X-men Set) and one with her modified X-Factor 2nd costume (As part of Marvel Heroclix: Deadpool set)