Of course there are lots of ways a story can develop without anyone being disagreeable (there has to be some kind of conflict to make a story, but it need not be interpersonal), and even more ways it can happen without a former enemy becoming a friend. "Redemption" (in whatever form it takes) of an enemy is, as far as it goes, a valid plot choice, but if the audience hate that character enough, it can be risky. Sauron can't just say, "oops, my bad," have everyone forgive him, and the story work. Cass in Artemis is at that point, for me (which the dev recognizes, giving a "F that bitch" option). Rachel in Cosy Cafe at least borders on it. Sarah in Cosy Cafe, Kali in Harem Hotel, and Alex in Eternum aren't--they're all pretty prickly to MC fairly early on, but warm up quickly enough. Shelby, to me, is more "Cass/Rachel" than "Sarah/Kali/Alex."
But from MC's perspective, these are very different. Jessica's a long-time family friend (at least, even without the patch), who's recently been kind of bitchy. Shelby has been an unmitigated bitch to MC and everyone around him, every chance she gets, until pretty late in as much as we've seen of the story. So while I can trust that Jestur will make her redemption palatable, I'm not especially looking forward to it. And for that matter, I'm not much of a fan of Jessica.