Roommates or former roommates could work pretty well. He respects peoples' privacy enough not to go in their rooms without permission, but there could easily have been a couple of incidents of knocking on the door while in the Zone. Especially if he was under the impression Walter was neglecting other things, like eating timely meals.

I'll need to think about the emulation side. I'm thinking Russell tends to emulate louder, more confident people than himself - if they're likeable and he behaves like them he'll be liked too, right?? But he appreciates wordplay, especially stuff he hasn't heard before.