Vongrak
I mean the program analogy is useful for singlets but reading up on plurality and systems would be useful for Kat and Lily considering how often they run into it. Although KatE is interesting because "sapient being that exists only as a weapon" kinda thing ha some interesting philosophical implications and of self-worth. Anyway I love where you've taken this, of alters and the melding together and splitting in certain cases. As someone who splits into a KatE and KatH in my own mind at times, it's relatable.