The thing to understand about Amy Dallon is that she's an incel. You'll make so many mistakes in trying to understand her character unless you start from this lens.
An abusive home life which encouraged emotional repression and resentment
An inability to change for the better, despite being socially and economically suited to do so (by virtue of being a parahuman)
Most importantly, a strong belief in the just-world hypthesis; in her mind, bad things only happen to unjust being, good things happen to good people, and doing good things regardless of intent/sincerity entitles you to a reward
These are all traits she has common with incels based on how they describe themselves and what they believe. There's this belief in the fandom that her sexually violent behavior came out of nowhere, but I posit that these character flaws, combined with Amy's knowledge that Victoria would never willingly reciprocate her feelings, provide the perfect setup for her to do what she did.
I don't think was an accidental writing decision either, like Taylor's attraction towards women. It really feels like Wildbow purposefully wrote Amy's downfall to parallel stories about "nice guys" who fly into meltdowns or become crazed stalkers after finding out that no, basic decency doesn't entitle the object of your affections to fuck you. Men who, despite real challenges, have the resources to become well-adjusted but refuse because they completely lack an internal locus of control. Just like them, Amy had resources outside of her abusive family in the form of the PRT, who despite their own issues would have moved heaven and Earth to make sure they didn't lose a valuable cape like her. Instead, she continued to hide her deteriorating mental health and continued to harbor feelings she knew wouldn't be reciprocated until she finally messed up like she'd always been meaning to:
"Do you know how many hours I’ve spent awake at night, wishing my powers would just go away, or that some circumstance would come up where I’d make some excusable mistake where they would eventually forgive me, but where I couldn’t visit the hospitals anymore?”
Another commonality with incels and "nice guys"; not wanting to actually get better, but waiting for a reason to let their worst impulses loose.
I also think this was the reason Amy's character drive Wildbow so crazy. Imagine, you write a character whose mental illness and entitlement cause her to rape and mutilate her sister, who has clear parallels to an incel's violent reaction to being rejected. The response by a not insignificant part of the fandom is accusations of bigotry, because they have invented a version of your character in their heads that has all of her identity markers but none of the characterization you wrote. Coincidentally, most of this part of the fandom hasn't read your work to completion, if at all. Some of them even blame the sister for being raped! This isn't helped by the fact that you are a bit homophobic, that you wrote your protagonist to be bisexual but didn't realize it, that you described the sexuality of one of your bisexual characters as "hedonist", that you inexplicably wrote a character who canonically looks butch, is obsessed with your female protagonist, but is somehow straight. Maybe you could have done some of that better, but the fact that your biggest detractors are fans of your incel rapist is confounding to say the least. Combine all this with the inkling suspicion that this discourse wouldn't exist if you had written Amy as a man...yeah, I kinda get why Wildbow went insane about her.
Now, I'm not writing this as some sort of callout for a fictional character. I love evil women and seeing Amy actually lean in to being an incel crashout would have been fun as hell. But I really hate this idea that Amy was a poor little meow meow whose character was assassinated by the author. The pieces are all there, you just understand this character less than Wildbow which is really saying something.
