a teaching/research 'fellow' [=a graduate student who gets money in exchange for teaching/research]
He attended the concert with a 'fellow' student. [=someone who is a student, as he is]
He has always tried to be of service to 'his fellow man'. [=to other people]
(..) We've been hunting together all our lives. I know when you're gonna go off on your own. You gonna leave me behind, too? As your fellow soldier, I suggest that you stay with your unit. But I couldn't stop you if you wanted to come. Hawthorne, Everdeen, (..)2015 The Hunger Games: Mockingjay - Part 2