Callisto was born in a villiage called Cirra. When she was about 12 Xena's army burned down her town and murdered her family. She was left tramatized and later later becomes insane.
She spent her early life with nothing on her mind but vengence and doing nothing but practicing to defeat Xena. Xena was fist introduced to Callisto when she was being blammed for mass murders that she did not do. Callisto was going on a rampage in Xena's name to lead her to her while doing damage to her reputation. When they first meet Xena is surprised to see that Callisto is not only as strong and fast as her but she can also catch her chakram, only 2 other people could ever do this. Xena ends up defeating her but could not kill her because of the guilt she felt for pain she caused in Callisto. Xena hands her over to the authorities but Callisto easily escapes and finds Xena again. Again Callisto cant beat her so she murders Gabrielle's new husband and takes off. Xena catches up with her and they fight and both fall in quicksand. Xena manages to get out but Callisto is stuck and is sucked under. Callisto works with Ares, the God of War, and they invade Xena's dreams where Callisto and Xena end up switching bodies. Of course Xena talks Ares into letting her return to Earth but still in Callisto body. Xena and Callisto fight and Xena remains in Callisto's body for a episode before Ares restores them.
Callisto agains escapes Tartarus by making a deal with Hera that if she can kill Hercules in one day she will be granted immortality. Instead of trying to fight and kill Hercules, which she knew she couldn't do, she posioned his family and talks him into going to the tree of life where one bite out of a golden apple will cure illness and eating a whole one will make a mortal immortal. She traps Hercules and gets an apple giving her immortality and her sanity. Hercules escapes and traps her in the labyrinth, breaking her sanity again.
When an Amazon named Velasca eats Ambrosia and is hellbent on killing Gabrielle, Xena makes a deal with Callisto that if she helps them she will get a chance at the Ambrosia, which will grant her powers. Xena tricks the two into fighting for he Ambrosia on ropes over a lava pit, Callisto gets and eats the Ambrosia and in that moment Xena cuts the ropes sending them both into the lava.
Callisto is freed by Hope, Gabbrielle's evil daughter, and talks her into killing Xena's son Solan causing a rift in Xena and Gabby's friendship. Xena fights Callisto and traps her in a mine where she stays traped for a couple years.
Hope agains frees Callisto and sends her back in time to kill Hercules and gives her the hind's blood, she fails to kill Hercules but does kill Strife. In her time travel it turns out that it was her who accidently killed her family by trying to protect them from Xena's army. But Lolaus, Hercules sidekick, also traveled in time and stops Callisto from going back in time making it so that the event never happened. By the end of the episode Callisto is traped in an interdimensional pocket. She later escapes in time for Hope's rebirth.
By now Callisto has so much pain she just wants oblivion and Hope promises to give it to her if she protects her during her transformation from child to adult, she spins a cocoon of goo around herself. Then when Gabrielle sacrifices herself and dies she laughs and says "now i have a reason for living!" but Xena stabs her with the hind's blood dagger sending her to hell.
She is offered to return to life if she can corrupt Xena and install Caesar as emperor of Rome and she cant
hurt Xena physically in the process or she is sent back to hell. She fails both missions and defeats Xena by breaking her spin with her own chakram. Xena and Gabby are both crucified and die, but there spirits go to Heaven. In heaven Xena encounters the demon Callisto and is so guilty that she switches with Callisto and becomes a demon while Callisto is an angel in heaven. Later Xena and Gabby are resurrected by Eli's efforts and Callisto the angel's spiritual aid and Xena is pregnate. Xena later finds out that her baby is Callisto being reincarnated as to make up for the death of Solan.
Powers & Abilities
Callisto's is an amazing fighter holding up against Hercules and Xena with no powers. With her powers she is immortal,super strong and fast, hightened senses, and can shoot lightning and fire balls out of her hands.