Welp, Anon of 708611833720913920 has now caught my curiosity - what would be the best way for either a human or a giant to get on Christopher's good side?
Oh boy, we're talking about pre-P1 Christopher here, aren't we?
I know I said I would probably be able to avoid being sold off, but honestly, it's going to depend on his mood that day. More than anything, he's practical - usually. Which means that, given the normal scarcity of humans, the most you'd get is a day or two of him keeping you to himself and teasing you before he'd start renting you out. He's seen it all. Fighting, crying, screaming, really, none of that is going to do you any good.
Unless.
Really, all you'd need to do is exploit his biggest weakness, which is that he's extremely weak to any sort of positive affirmation. He might be a little confused at first if you were a human, and he would certainly do his best not to let it show, but he'd definitely be...intrigued. He would not understand why anyone, much less a human, would be nice to him. Bonus points if you enjoy being eaten.
The other thing about Christopher? He gets kind of obsessed/attached. Like...really obsessed, especially if you show him even a crumb of validation. If you kept up being nice to him, you'd probably have him tripping over himself in a few days for you. This would certainly help jumpstart his "humans are people too" thinking, and if you're lucky, you might get a full 180 out of him. Maybe.
The only problem is...he really doesn't make it easy to be nice to him sometimes. So good luck with that XD