I'm not sure its a humiliation fetish. Chris is just shameless, and has been humiliated a lot. My argument is if Chris had the fetish we would see it plain as day throughout Sonichu. But we don't. We get the opposite. Narcissism, and an inflated ego oozes through Sonichu. We wouldn't get the uncomfortable and irrational love the Sonichus have for Chris. They'd probably hate him, Chris would be losing most of the fights, and of course the villains would be humiliating him in sexual ways. Sonichu was the opposite, it showed Chris getting back at people for humiliating him in real life
There's two types of fetishistic gratification.
1) what you describe, the extremely obvious overt "I seek this out" and it becomes an obsession. In dangerous/unhealthy levels it can get classified as a paraphilia, like voyeurism, or flashing, or corpse-fucking, anything illegal and harming quality enjoyment of life. Generally, this first one (though not to a paraphilia degree) is what everyone thinks of for fetishes, because it is pretty fucking noticeable, and easiest to cater to. Vore, for example.
2) the second is the other that has been suggested, in this case, and it's developed out of experience, circumstances, and restricted access. A woman in an all-girls school, prison, career etc. Might not normally be bi, or into poly or orgies, but their own sexual experience being other women might make them gradually insecure, and try to justify liking it with "it's just my thing" -- not even consciously, but on a deeper level. Most people believe this is part of why rape fanfiction and porn books are so fetishized among (a certain population of) women, because
A] it's guilt-free. Being a slut is bad, but western society tries not to victim blame, esp. rape
B] it's often held as "coping" I can't personally say, I'm not a pro, nor have I such a fetish, but it's SAID a lot.
C] Obsession with avoidance inevitably leads to obsession with the very thing you meant to avoid. Ie: "stop thinking about the white polar bear in the white snow. What are you thinking about?" Sort of a psychological Streisand effect. This is why preachers always screaming about gay sex is bad, often had fuckboys of their own. Obsession with "don't get raped" lives so rent-free in some skulls it becomes "fuck it, rape is kinky."
D] Reluctant gratification / timing. - which has been specifically mentioned for Chris. A normal person who orgasms right as their parents knock, is going to hate it, but not let it become a reoccurring dominating theme in the rest of their life. Chris ain't normal.
Chris' art had all of his overt fetishes, especially fingering pussy, which the troon squad convinced him is because he has pussy envy (leading to exacerbating his obsession, and the unclit) but his real life had the humiliation, so constant that the only way to sort of "deal" with it, was to accept it. He didn't just accept it either, he did purposely seek it out. That's why I think it's a type 2 fetish, not just "well he had sex with a guy once and no woman will touch him so..." circumstancial gay style, but actual fetish. Where it's just all so associated ("being humiliated means I get to come!") and mixed up in his brain and the lack of healthy coping skills to untangle it. Plus, he doesn't NOT want a woman to mommy dommy him, he just didn't want it first and foremost during his initial "want girl" stage.
"Does Chris enjoy being humiliated now?"
Go watch him giggling at how "it feels good!" When the cops were checking for weapons and Ralph was screaming dumb shit. He's not into it to the level of being willing to put more than the bare minimum effort into it, it doesn't wholly jive with his ego/id how he wants to be seen (lol persona) but yeah, he's had probably more sexual experience with being told he's a fuck-up than literally anything else. Note: he told ppl he was Barb's best lover forever and able to hit her G-spot like Bob couldn't etc. But that's his ego, not his fetish. The fact that he told all this to Josh and a few other trolls, THAT'S his fetish.