When I talk to him, the only option is: "Do we make a good team?", he says yes and then DURAS RESPECTS YOU comes on screen. He doesn't come with you though. Some "respect" that is. Could be a bug.
Haha, yeah, the whole Duras thing is fucking hilariously bad. You go do a long-ass questline for him, in multiple areas that you reasonably shouldn't even be in for most of the game, judging by the opponents there, and his like for you goes from Neutral to "True Friend", and
then he can come with you and he pretends like you're the best friends for lyfe. If you actually engaged in the game in a sensible manner ("Hurr durr don't pump 200 arrows into an enemi just don't go there") you wouldn't acquire Duras until you're level 15 or something.
I think they intended for you to go for pure combat skills in the beginning, get the next tier of weapon, beeline it for the quest to pick up the Converter parts (which was hilariously bugged for me, btw, obviously, since this is Elex we're talking about), and at the end of that area, pick up the autistic CNPC and just faceroll pretty much all enemies ever, because he's absolutely fucking insane with his ranged weapon - as long as you don't try to get the high ground, because then the idiot starts to shoot into the ground, because this is Elex and the AI is retarded.