Ryan Holder is your classic frenemy.
On the one hand, he shows Jason a great deal of respect for his scientific prowess, telling him that he "would've changed the world if [he'd] decided to go that path" instead of "teaching undergrad physics to future doctors and patent lawyers" (1.139). On the other hand, there's totally a competitive undercurrent to the two men's relationship—which is most evidenced by Ryan's little crush on Daniela.
We see this same conflict playing out in Jason2's universe as well. There, Jason is the scientific luminary, while Ryan is the one getting busy with Daniela—though their relationship doesn't seem all that serious. This isn't the only role reversal, either: Ryan2 clearly resents Jason2 for being so successful in his career. Jason2 even won the Pavia Prize for his research, which is something that Ryan won in the prime universe.
That being said, we don't think Ryan is such a bad guy. He might be misguided at times, and he might be condescending to his old friend and former roommate, but he doesn't do anything monstrous. Sure, ratting Jason out to the bigwigs at Velocity Labs probably wasn't a smart move, but he had no way of knowing the can of worms he was opening.