Gus: Zwei at the time of writing desires purpose.
Like —I assume— most Hunters, he of obviously loyal to Beacon but Zwei lacks any real strong ties to things that aren't his friends and (new) family. I suppose a part of him thought that getting into Beacon might give him that feeling but with how mediocre he is, that idea is almost lost as he has found himself frustrated at how little he can actually change but without as much motivation to actually improve himself as he really should.
I really enjoyed this question, I honestly hadn't thought of this as much as I probably should be, thank you!