As wretched as Yeager's behavior is, I'm pretty shocked at Cyrus. The repressed scientist is losing his grip even when he's not changing. Yeager is meant to be evil, so I expect nastiness from him, but watching Cyrus get friendly with Maggie's gloves was even creepier than the scene by the docks, IMO
Yeager was the only "human" antagonist in DS that ever particularly scared me as a young 'un... Bad nose and all. Thank God they got over that lil phase quickly.
I think the key here is that Cyrus and John are more the same person than either realizes. John is the person that Cyrus secretly wants to be. I mean, I look at him and you can practically visualize the newsfootage of police digging up his backyard and finding multiple body parts while the next door neighbor is saying "He always seemed like such a nice man..."
If Sabrina had drunk Cyrus’s potion, what would she have been like?
I imagine that Cyrus was so repressed that he had no idea what he really wanted until he heard about Yaeger’s misdeeds. Then suddenly he had an exact image of what he wanted, and he had to have it.