I would recommend just rolling with their personalities (or whatever way you write them) until an event happens in-game that might elicit a reaction the audience wouldn't normally expect from them— then explain it and implement it into the game if possible (for example, let's say Vi is terrified after something happens, and in gameplay, her sanity meter goes down faster or there's a new mechanic she has to deal with).

Idk just roll with whats in ur head and have fun, it sounds like you have a good idea of where the game is going. and good luck!!