I think that an underrated element of Chris's experience is the slow entropy of his daily life. A lot of attention is focused, naturally, on the big moments, where the kind of drama that makes for good rubbernecking happened. And these moments were probably pretty transformative for him- it's the moments of high stress that modify a point of view (insofar as a person's point of view can be modified after childhood at all).
However, much of Chris's behavior only begins to make sense when you cross-reference these big moments with the slow grind of tedium that takes place for years and years between them. In all the periods when kiwis etc are losing interest, hopping off the train, and going back to their other lolcows, Chris was still right there, spooling in the narrative thread of his life.
So it's the pattern of daily life that constrains a person's goals (what they want is relative to what they already have) and it's the big narrative moments that constrain a person's methods (what they're willing to do/how far they'll go is informed by how things have worked out for them in marginal situations).
So in his daily life, Chris has almost nothing. He lives in squalor, he's extremely lonely, he's stuck with a woman he probably hates, he has no one to talk to irl. It's basically just a continual stream of ego-deleting media and fantasization, diddling exhausted desensitized seratonin receptors to distract himself from the misery.
In this respect, he's not too different from other NEETs; but they don't tend to rape their mothers. To figure that part out, we need to look at his behavioral constraints.
What SHOULD Chris have been doing in his situation? What would a "normal" person, minus Chris's particular trauma, do with his resources and his desires?
The obvious answer is to sell out, and that's what everyone was telling him to do. Null even got him to take the first steps towards it, right before things fell apart. He wants friends, sex, and toys, and he has a bunch of fame. It's natural to trade the latter for the former- money lets you go to cons, buy toys, and hire hookers.
Chris should have sold out years ago, and he didn't. Rather than selling out, he's taken a swift spiral into some of the darkest places a person can go.
With all this in mind:
A: Chris's desires must include something other than the standard NEET set. Motherfucking doesn't really scan as a way to fulfill sexual desire. It's almost certainly motivated by something specific involving him and barb. He wants to inact some sort of transcendental change on her.
B: Chris's constraints prevent him from selling out and fucking off. Some big experiences in his past must have convinced him that that's not an option. Maybe it's that he feels he can't trust anybody (even Null) to help him with it, maybe it's something else.
C: Chris lacks constraints concerning incest. This is obvious; but I think that these constraints must have been lost (he's not a potato, he understands right and wrong). Most likely he lost it somewhere along the idea guy era and his budding schizoaffective disorder. There's some specific rationalization that's overwritten the script that must have already been there; incest, especially parent/child incest, isn't some shit you can just not learn the rules about.
Here are some possible constraints that might make his behavior make sense:
"No one on the internet/outside of my immediate environment is real"
So much of Chris's life story involves people telling him to ignore trolls, that the internet is meaningless. This was good advice before he was famous, back when he could just walk away. But now that his fame is his biggest financial asset, any tendency he's internalized to treat the internet as "not real" undercuts the potential for gain there, as well as the consequences of spilling his secrets to internet people. That explains why he isn't trying harder to do the eceleb thing, and why he hasn't learned by now to treat trolls as dangerous.
Also, if no one on the internet is real: "I have sexual desires" ->"Porn isn't real enough to satisfy them" - > "I need a real woman"-> "People I don't interact with in person aren't real" - > "The only real woman I know is barb"
This chain of reality-logic isn't enough to lead him to rape barb, though. Part of her appeal is that she's real, and all normal constraints should apply to real people. So something else has overwritten that. Here's a contender:
"Boundaries are made to be broken"
Pretty self explanatory. The Troon shit, the woo shit, the dimensional merge shit– all a way of saying that norms need to be smashed in order to create a society where Chris can be happy/normal/loved. There's a reason everybody plays Komm Susser Todd. Same shit; the natural conclusion of the leftist desire to lower the floor of acceptable behavior in order to make everything acceptable and eliminate all criticism (criticism and ostracism are opposites here-one is personal, one is impersonal).
But it might be something specific about him and Barb. It'll be easy to tell from how he explains things going forward.
I'd honestly say that in 8/10 realities, Chris-chan sells the fuck out five years ago and everyone gets bored because all he does is sling merch and get into pissing contests with YouTube people. However this nightmare shit came about, the only way to make sense of it is to look at what specifically has happened to him in the last decade (what's warped his constraints), and his early childhood (what's warped his desires).
