The single deadliest Skrull in the empire is here on earth, and he's coming for Dorrek. Despite the fact that Dorrek has turned his back on his destiny like a spiteful child, his presence could put a stop to all of this. ... This is your home...this is my beloved's home, and now it is mine. I'll die to save it. Will you?
Xavin was a Skrull who came to Earth to find Karolina Dean, who was betrothed to her. Karolina's parents promised their daughter to Xavin's parents, under the assumption that they, along with Xavin, would perish while attempting to fight the Majesdanians (the alien race that Karolina belongs to). Her parents died before finding out that not only had Xavin survived, but she was training to become a Super-Skrull, meaning that in addition to her shape-shifting abilities, she would also have every power that the Fantastic Four had, although as a trainee she could only use one power at a time.
Upon arriving in Los Angeles, Xavin encountered Karolina and her fellow Runaways, Molly Hayes and Victor Mancha. Karolina was already feeling down, having recently revealed her homosexuality to Nico Minoru, a girl she pined for. At the time, Nico said that she wasn't a lesbian, and that she couldn't return Karolina's love the way Karolina had hoped. Due to a misunderstanding, a fight broke out between Xavin and the Runaways as she tried to convince Karolina to come with her and be her bride. While the Runaways escaped, she pursued them, and threatened to kill all of them if Karolina didn't hear her out. She was eventually able to tell her that, while she wouldn't force her to marry her, she hoped that she would only come with him to witness the animosity between their two races. He believed that if they were to marry, the war between the Skrulls and the Majesdanians might end. Though he could call off his army, the Majesdanians would not be so merciful and would destroy Earth for its indirect part in the war.
The Runaways tried to persuade Karolina not to go, stating that it was wrong to force her into an arranged marriage, but Karolina didn't want to go because she wasn't attracted to men and didn't want to live a lie. Xavin reminded her that for a Skrull, switching gender was easy, and he took on the form of a beautiful young woman. She eventually persuaded Karolina to go with her, and she and Karolina began to truly care for one another. Xavin even went as far as to train (after going through forty years of radio broadcasting) the wedding band to play Lucy in the Sky with Diamonds, one of Karolina's favorite songs, because she was feeling homesick.
Unfortunately, things didn't turn out as planned when a fight broke out between the two races during the wedding ceremony. Xavin and Karolina barely escaped before the planet was destroyed, and they returned to Earth, only to find the Runaways fighting each other while Molly was in the hands of the new Pride. While the Runaways went to retrieve her, Xavin claimed she would stay behind and guard the Hostel. Instead, she and Nico devised a plan to retrieve Molly. Xavin impersonated Nico and took a bullet for her. The shot would have killed Nico, but it barely injured Xavin. She was then able to distract Geoffrey Wilder long enough for Nico to untie Molly.
Xavin joined the Runaways, but had trouble adjusting to her new surroundings and getting along with her new teammates, particularly Victor (whom he often offended with her derision of robots). During a trip to the past, Karolina was pleased that when Xavin lost concentration, she reverted to a female form instead of a male one.
When the survivors of Majesdane wanted to imprison Karolina, Xavin took the place of her beloved.
Skrull Shape-Shifting: Like other Skrulls, Xavin is a shape-shifter. They can mentally cause the unstable molecules that comprise his or her body to become pliant, enabling him or her to assume other forms through muscular expansion and contraction. Once a new shape has been assumed, it takes a conscious act of will to assume another form or revert to natural. Hence, Skrulls do not spontaneously lose their assumed form when asleep or unconscious. Skrulls in altered form will, however, revert to their original forms at the moment of death.
Skrull Military Training: Xavin is a trained Skrull soldier.
Aviation: Xavin is trained in the use of the advanced warp-drive starships of the Skrull-military.
Unarmed Combat: Xavin is trained in the unarmed combat of the Skrull-military, he is also quite experienced; due to his involvement in the Kree-Skrull War.
Marksmanship: Xavin is trained in the use of the ranged energy-weaponry of the Skrull-military.
Skrull Shape-Shifting: Skrulls only take on the appearance of an object or person and none of that object or person’s characteristics. There is a limit to the size of the object or person a Skrull can imitate. The average Skrull cannot distend his or her mass any more than 1.5 times as large a volume as his or her original volume, nor can he or she contract his or her mass any more than 0.75 a volume as his or her original.
Power Limitation: Xavin is currently, only able to control one power at a time.