Romulus is the first specimen of "Lupus Sapiens", an old species of beings that evolved from wolves instead of apes. He has been alive for thousands of years. What we do know of him has been revealed, presumably by Romulus himself, to Wolverine in dreams. Wolverine's first dream depicts him as a shadowy figure standing astride a mountain top. He's shown to be watching a battle taking place below him between two groups of Lupine's, one dark-haired and the other blond-haired. His next appearance is apparently in the same time, showing him throwing a dark-haired Lupine, who has just massacred an entire tribe of prehistoric men, in a fire causing him to be severely burned. He then throws him in a nearby lake, waking him up, before disappearing. In the next dream he leads an army of Lupine on Elephants into battle. Romulus is the same Romulus who founded Rome from former barbarian tribes. It is unknown how many stories about him are true or myth.
Romulus was created by Jeph Loeb and Simone Bianchi.
Romulus seems to be the Alpha to every lupine mutant, like Wolverine, Sabretooth, Wolfsbane, Feral, Wild Child and Thornn. Wild Child even goes as far to call him "my master".
An example of which would be his interactions with Daken. He first revealed himself to Daken after the deaths of his adoptive parents stating that he was what the boy would one day become. He later had Wild Child spend months torturing Daken all with the simple message of "stay away from your father". It has been shown that Daken has a strong sense of loyalty to Romulus, and implied that he sees him as a father figure.
He has some kind of link with Weapon X, because he was the Wolverine's adamantium injection promoter. Moreover, he must have an amazing knowledge of genetics. He said that Charles Xavier and Mister Sinister were "fools who stumble around in the dark, trying to understand genetics". And he demonstrated it by reverting Feral and Thornn to their feral forms and eliminating the human part of Sabretooth's mind. All we know about him is that he covers his scent with perfumed oils, and that, throughout History, he has been a barbarian leader and a Roman Emperor.
Gloriam ad Romulam
Wolverine's next dream depicts Romulus during the Roman Empire. Wolverine is an amphitheater witnessing the combat between two gladiators and a group of tigers. While one is badly injured, the other manages to continue on and defeat the animals. Turning to a waiting Romulus, shown as the emperor, he informs him that he awaits his decision. Romulus replies with a thumbs down, leading the Gladiator to decapitate his fellow. As the head rolls away, it is revealed to be another blond-haired Lupine. The final dream involves Logan himself. He is reminded of one of his first encounters with Sabretooth. He is in Japan, engaged in combat with Sabretooth and attempting to murder him as the Hand had ordered. Romulus appears and puts an end to the conflict, preventing Logan from ending Creed's life.
In the present day Romulus' influence has only just now begun to be felt. Romulus augments the already formidable abilities of Wild Child. He then sends him to retrieve Sabretooth who is being held captive and interrogated by Black Panther. As Wild Child interacts with Creed upon entering Panther's Mansion, it is revealed that Creed is frightened by the mere mention of Romulus' name. Wild Child is able to retrieve Sabretooth, and in the process manages to wipe the floor with Wolverine, and returns him to Romulus. Romulus then manages to erase all vestiges of humanity form Creed's mind. He then sets the wild Sabretooth loose on Wolverine as he invades the Weapon X program. Falling unconscious after loosing to Creed, Logan has yet another flashback. He recalls when he was himself a captive of the Weapon X program. He is in his tank, being monitored by the Professor and Sabretooth. Romulus then enters the room. He admonishes Creed for getting carried away, causing him to reply with obedience. It also reveals that Sabretooth has always known of Romulus and his actions. Romulus also makes an offhanded remark about his own knowledge of genetics compared to those of Xavier and Essex. His comment is confirmed by the Professor, who credits Romulus with the very existence of the Weapon X project.
After Wolverine had finished off Sabretooth with the Muramasa blade, Wild Child appeared to confront him. During their conversation he revealed that Romulus himself was responsible for Logan's flashbacks. He also let slip that two Lupines always emerge from the pack, one dark and the other blond and that only one can survive. This comment helps to partially explain the majority of what has been revealed about Romulus thus far, as well as Sabretooth and Wolverine's own rivalry. Romulus himself is then heard speaking, presumably from behind Logan, saying that everything Logan has learned about his past has been true. He then disappears with Wild Child, remaining undetected by Wolverine.
Wolverine with the help of Deadpool came up with a plan to draw Romulus out in the open. Wolverine stabbed Daken with a fake Muramasa blade. This made Romulus come out of hiding to see if Daken was dead. A fight breaks out in the street with Wolverine and Skaar vs Romulus and Daken. Romulus escapes with Daken, the next day Romulus thinks he is safe but Daken has other plans and tries to kill him. Just as he is about to deliver the killing blow with his Muramasa claw. Romulus is teleported away. Now Romulus is trapped in the Darkforce Dimension by Wolverine and Cloak with no hope of escape.
Romulus possesses various superhuman attributes, the full number of which are currently unknown. Romulus possesses an accelerated healing factor that lets allows him to fully heal damaged tissue. The full limits of Romulus' healing powers aren't known, but the overall speed and efficiency in which he heals appears to be based upon the severity of the injury. He heals from slashes across his face from Wolverine's claws within a matter of moments. However, from the deep slashes across his upper body that ends the fight, Romulus leaves still holding his side as the wounds continue to heal minutes after they've been inflicted. Romulus' healing powers also afford him great resistance to drugs and toxins as well as immunity to conventional diseases. Romulus possesses some degree of superhuman strength. As with much of his powers, the full limits of his powers aren't known. However, he has demonstrated sufficient strength easily lift Wolverine by the wrist off the ground and hurl him repeatedly across a room with no discernible effort. While most of his past is unknown, Romulus has been alive since prehistoric times. Hence, he is tens of thousands of years old. In spite of his age, however, he has the physical appearance and vitality of a powerful man. However, Romulus appears to be showing some signs of aging. The original color of his hair was black but now, it's mostly white with only a few areas retaining his hair's original color. Romulus possesses a single, retractable claw at the tip of each finger. The claws have a razor sharp edge and are capable of cutting material as durable as bone. It is possible that his claws can cut much tougher material as well, but it's unknown at present. Romulus has demonstrated certain telepathic abilities of undefined limits. Wolverine himself has learned that many of his memories at various points in his life have been removed by Romulus via telepathic means in order to manipulate Wolverine in various situations for various purposes. In his recent battle with Wolverine, he was able to create a vivid telepathic illusion of Wolverine's deceased wife Itsu. However, Romulus' psionic powers are substantially inferior to those of Professor Xavier as Xavier used his powers to help shield the minds of Wolverine and his other X-Men from intrusion during their association with them. Furthermore, Wolverine has also learned to shield his mind greatly against telepathic intrusion, limiting Romulus' powers over him even more. Romulus is also shown to have a mastery over a wide range of weapons. Including katanas, shurikens, an assortment of projectiles, and a multitude of other weapons. He has also been shown to wear a set of gauntlets which contain four adamantium claws. Also, he wears an armored knee guard on his right knee.
As has been stated and shown against others, Romulus is vulnerable to the Muramasa blade. The blade itself inflicts injuries that greatly nullifies the effects of superhuman healing abilities. If Romulus were to sustain injuries to a vital area of his body, with the blade it would take longer to recover.