Is my friend a sociopath?

i have a friend named (marcus) he is friendly to me and a few others but theres a boy at my school named george ..george has a weight problem and is very humble and quiet ...and my freind marcus always humiliates and dominates george because he knows george won't get in his face and fight back. i wouldnt call marcus a bully because he is a pretty popular guy but he always messes with people who won't fight back .....when it comes to someone his size or someone who dosent want to be screwed with ...marcus acts serious around them .... i wouldn't call him a bully but he might be a sociopath .... he made fun of a kid named jonathan .. jonathan has a lazy eye and i told marcus not to make fun of him because jonathan was born with it ...marcus just ignored me and kept laughing at him. i feel as if he has not empathy for defenseless people...... should i tell him what he is doing wrong? or what? he is 15 and i am 14 ..i hear that sociopaths have to be 18 and older ......and i have asked this question before and people think im calling him a (phsycopath) but im not i mean (sociopath)