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]
(..) as this must be surrendered to Lugash authorities before departure. The loss of this card may cause considerable delays. Have my bags sent up to my room like a good fellow. How are you, Pepi? Ah, what a surprise. Sir Charles Litton, isn't it? Not necessarily. Un Cognac, (..)1975 The Return of the Pink Panther