Caitlin snow is foe or friend in future?
She's the one who helped Barry/The flash in very manner she can. It,s like they are The flash team .It will be really sad seeing her turning into villain.It's Caitlin Barry's one of the really closest friend. According to a comics edition of firestorm "Killer frost" who is a well known DC villain has original name as Caitlin snow .So basically in future episodes may be we could see her as killer frost or may be not! It might be be possible that if they introduce killer frost she'll be some other person. The reason is she really cares about Barry which we can see in the previous weeks episode Revenge of the rogues in which she's desperate to even die for The flash.
The origin of killer frost according to new 52 issue is due to a thermodynamic engine which she went to repair in arctic but soon the place is covered by H.I.V.E agents and for saving herself Caitlin frantically ripped off coolant merging her body with ice. The show creators will change the story or not it is still a question. Nothing is confirmed and nor any rumours for this may it will happen in second season .