It honestly lowkey disturbs me just how many people want Gabe to be even worse than he already is…? The amount of people who are thirsting for violence…in a kid's show. Like, are you guys OK?
I mean, as someone who has had my fair share of abuse, let me paint all the ways in which show!Gabe matches the Gabe in the books (and even, sometimes, goes beyond?):
He controls the entirety of a living quarters that he doesn't actually pay for. As Percy points out, Sally is the only one with a half decent job; and we all know that, even if Gabe has a job, none of that money is going towards his wife or his stepson.
It actually kind of disturbs me to think about how Sally and Gabe even got married, or if they even are legally married. Since, how would Sally have paid for it because she has no parents, and it's usually up to the bride's family to pay for some if not all of the ceremony, if I'm not mistaken. I've never been married, but I know enough about it to know that it's likely they're not actually married, and that's another reason Sally didn't feel obligated to take Gabe's last name. I think it's more that he trapped her into that situation given that she was a single mother with a young son and no support system, and she only stayed because he's a vile piece of shit whom not even other monsters would bother approaching.
He gambles away his wife's savings, which leaves her scrounging for money to care for herself and her son. She's also got no other family, so if something truly bad were to come up, she'd be shit out of luck, and her and Percy would basically be homeless and destitute.
His immediate first interaction with Percy is to belittle him by calling him Genius (In the book, he constantly called Percy 'Brain Boy' in an insulting way, thus mocking Percy's intelligence and his ADHD without actually using the words; in either context, that is still verbal abuse) in a scathing way, and then gloating because Percy got kicked out of Yancy. By both his actions and his words, he shows, with zero hesitation, just how little he cares for either of them, Percy or Sally.
He actually had a glint in his eyes when Percy described the reason he was kicked out — bullying another student. It's not spelled out for the audience, but it implies that Gabe actually praised Percy for being violent. He liked that his stepson demonstrated violence against another student. I'm not a parent, but encouraging a kid to do violent acts against other kids is really not good parenting.
This also implies that Gabe might get off on violence or has a violent streak of his own. The whiny, man-child facade is a staple of many narcissists and people who have violent tendencies. They use that child-charm to get under people's skin and then to control every aspect of their lives. The violence comes when the abuser's victims fight back or stand up to them. When Sally stood up to Gabe, notice that his voice got higher, and he became more belligerent. I'd hazard that if Percy wasn't standing there, it may have escalated into a physical fight in which Sally would have been seriously hurt.
Note that Percy does come to the conclusion later that Gabe was actually physically harming his mother, likely when he, Percy, wasn't around. This is a classic case in narcissists and abusers. They paint a pretty picture on the outside so that others don't become suspicious, but the inside is anything but pretty.
That he has a gambling addiction implies that he may have other addictions. It's a stereotype but true nonetheless that many addictions go hand in hand. He could be abusing alcohol or even recreational drugs. The films, while wholly inaccurate, did show Gabe drinking and implied that he has issues with substance abuse.
Even though Sally is said to be quiet, calm, and entirely too kind to be swept up by someone like Gabe, that could also be a product of his influence over her and may have just gone entirely over her son's head, being in his POV. Also, even the quietest and calmest victims will sometimes stand up for themselves or act out against their abuser if they feel their needs aren't being met. Or, in Sally's case, her son and her wellbeing were being compromised and she snapped.
Just because Gabe isn't smacking Sally and Percy around in that scene does not mean he isn't capable of it. And do we really need to see a grown man slapping around a child or his mother when that kid already had enough to look forward to?
Some of you honestly need Jesus — I mean Poseidon — and it shows. Really, I hope you all are OK and if not, that it gets better. <3