The eldest of four siblings, the younger three all girls, Kyle was always a quiet kid. Coming from a wealthy family, he was alwys very well off. On the surface he seemed to be pretty well adjusted. But on the inside, he craved to be like his sisters. He started secretly dressing in their clothes while growing out his hair. It helped that he was very feminine in appearance.
In college he finally got a chance to be the person he always wanted to be. He took on a distinctively goth lifestyle, hoping to blur the lines between male and female. But he was happy being who he was, not wanting to change a thing. His only friend in school was Steve, his roommate.
After being invited to an exclusive Halloween party at the Delta Beat Zeta House, Kyle met a pink haired firecracker named Degna in a local costume shop. She took an instant shining to him. At the party, Kyle soon discovered the truth: the Girls of DBZ were vampires and he was their newest recruit. In the end, Degna was unable to go through with it and Wisteria staked her. Then she proceeded to convert Kyle into the fold.
Katie is the wild, out of control alter ego Wisteria implanted into Kyle's new body. She was the apparent victim of amnesia, a "side effect" of her convertion. Katie has problems controlling the blood lust. After an encounter with a pink haired girl, Wisteria believes the conditioning is failing and tries again. During this time, Kyle is able to break free from the prison in his own mind. After a few attempts---and a fight for control---Kyle is able to regain his body and lock the wicked "Katie" up inside.
Though "locked away", Katie seems to be able to still communicate with her other half. She has started to fight for control again.
After successfully gaining control, Kyle reunites with his roommate Steve and the spirit of Degna---who is somehow stuck in some kind of limbo. Apparently Kyle is the only one who can see or hear her. Degna is able to give Kyle---Kylie---a crash course on being a vampire before he goes home that night. Upon entering the House, Carmilla discovers that Kyle has broken Wisteria's spell, which interests her a great deal.
Carmilla renames Kyle, "Kylie".
Convinced by Degna to help Carmilla, Kylie sets about to discover Wisteria's secrets---including a way to break the curse that is keeping both Wisteria and Carmilla bound to Ravencrest, unable to leave.
Though not fully realized yet, it would appear Kylie has the power to see ghosts---as evident by her ability to see and talk with Degna.