User blog comment:Thegamingknight4272/The return of Caitlin Snow?/@comment-24152851-20170430012611/@comment-3221148-20170504124229

Killer Frost is not a split personality, which she recognizes herself: Caitlin snow is fully conscious throughout the experience, she's not "taken" by something like the personae from "Split".

Her "evil" is the result of botched biochemistry related to the mutation. It's also why they talk about Caitlin being fully or not fully mutated this ep. She basically has three phases:

1) Using ice powers and getting somewhat whiter in the hair, but without eye color change: full control over her powers, shown in the Christmas episode.

2) Ice powers and eye color change: losing control over her emotions, verbally (when they were healing Iris) and later violently (in ). Can "snap out of it".

3) Ice powers, full hair and eye color change: her prior character is but a memory to her, though she's still able to act (or not act) on those memories, but cannot snap out of it on her own.