Okay, I'm going to try and make this short. Or as short as I can with so many characters. >.>
I'll start with Oliver, since he's a fellow staff member and thus more likely to interact with Tom! Umm. Mr Kendall is one of the English teachers, so you know he hangs out in the library a lot. He's also the Communications teacher and the Film teacher (omg, how did he end up with so many jobs? D:), so likewise, I feel like both of those will mean quite a bit of library time, assuming the films are kept in the library too... Other than that, he lives on campus and would be more than happy to help Mr Sawyer get settled. I see in his profile that he has a fair few brothers, which Oliver can relate to... Alright, I'll stop grasping at straws now and just assume that they'd get along well! :)
Jace here is just as new as Mr Sawyer, so they can be newbies together! He's more of an artist than a reader but he does like to get stuck in now and again, as he has a pretty big imagination. The library is probably one of the places he'll opt to hang out at too, since it's quiet and good for concentration. So I'm sure they'll bump into one another sooner or later!
Riley likely avoids the library for the most part because he doesn't want to be seen as a dork (he's so closed-minded when it comes to stuff like that. >.>), but if he can sneak into the Science section unnoticed, Mr Sawyer will be able to find him there. Chances are, hell probably stumble across him sooner or later. Just keep his cover and don't tell anyone he was there and they'll get on.
Evan also tends to avoid the House of Books, as he calls it, unless he really has to go there. Mr Sawyer is likely to see him trailing Ron and looking pretty lost if he ends there at all, but in terms of personality, he's totally the sort of student to engage Mr Sawyer in conversation before getting told to shut up because libraries are quiet and I'm not entirely sure Evan knows the meaning of that... :P
Aaaaaaaand Caleb is likely to hang out there as much as the average student, but he's nice and will probably be happy to chat with Mr Sawyer should they bump into one another too. :)