Could me and this guy go from being friends to boyfriend/girlfriend?

There's this guy (I'll call him Bob) and he and I get along great and we LOVE to talk during free time in class. I'm in the 12th grade and Bob and I only have 2 classes together. He gets kind of upset when I talk to other people and not him.

Bob sits on the other side of the room (due to seating arrangements) and he'll during free time... sit in the empty seat behind me and we'll talk like we're two best girlfriends.

There's this one other guy who I'll call Fred and he has outwardly told me he likes me. Fred will get really really close behind me when I'm walking to class (Fred's in the 2 classes with Bob and I). Fred will also try to touch me and corner me whenever I rarely happen to not be talking to Bob. Fred also talks very dirty to me and I have no feelings for him whatsoever!

Bob and I have a great connection and chemistry! He's a true gentleman and he seems to care about me. I would love to be his girlfriend and friend! I think he would love to be my boyfriend also!

How do I make him aware that I'm interested in him? Without being upfront? Is it possible to go from friends to lovers? Does he sound interested?

You can talk to Bob more outside of class, during recess or lunch