Does Percy ever have any trauma from Gabe?
I mean, in Tartarus, he says it smells like Gabe and I cannot fail to acknowledge his self-esteem issues which Gabe contributed to, but I mean more specific trauma like hating beer and gambling, etc. Something like that?
Percy has suffered due to Gabe for a long time, which contributes quite a lot to his trauma. You see, Rirodan was writing a children's book, and he didn't want to go down too many uncomfortable details, but the signs were there. A lot of them. And despite the canon's inconsistencies, Gabe is at least mentioned in accurate context every small time that he is referenced.
Rick, however, just to be safe, makes Percy's personality so that Percy avoids thinking of Gabe, and rightfully so. Let's take this slow. Because two important things, Percy's situation in the first book and all his issues are due to Gabe and, of course, he carries forward trauma from those situations, so what are they?
1.
Physical abuse is a part that is usually glossed over by the readers to some extent, even though it's in the first book. What I am trying to say is it is always acknowledged that Percy was abused, but rarely does the fandom go down the rabbit hole of specifics. If you see it once, you won't stop seeing it.
Gabe has both verbally and physically abused Percy so much that he has an extreme amount of self-esteem issues and a self-depreciating personality.
Not only did Gabe abuse Percy, but he also made Percy work part-time jobs or side hustles just to get extra money from Percy. Mind you, Percy was barely 12 in the first book, probably still 11, and this had been going for a while.
2.
If that wasn't enough Gabe controlled the budget of the family, not allowing Sally to spend more than he allowed and he splurged most money gambling so Percy grew up in very poor conditions but was sent to boarding schools with rich people which led to a lot of bullying from their end. Since Percy fought back, he somehow earned the per usual misnomer of being a troubled kid.
Cue all his expulsions. Some may be due to monster business, but most were definitely due to Percy fighting against bullies. Why is that notable? This is the start of Percy's anger issues. Percy has a lot of repressed anger from home due to Gabe and not being able to fight him (he hasn't tapped into his power yet, at least not enough of it). Plus, the bullies and horrible living conditions all contribute to Percy's attitude.
3.
Now, if you remember, in Book 1, Gabe threatens Percy severely so that he won't harm his car. But Percy was 12, and he himself says he wasn't going to be driving, but that wouldn't stop Gabe from blaming him. This means Gabe blamed Percy for everything, relevant or otherwise. We can see this in Percy's behavior when he immediately correlates every mistake as his fault and is always reflexively seen taking the blame for everything, even those that weren't his fault.
This scene actually creates a nice parallel against that scene in Book 5 where Percy is on a drive with Rachel in Paul's car and he is very suprised that Paul himself offered the car to him and didn't even impose any rules on Percy. He is however very worried when Blackjack dents the car because even though Paul is not Gabe, Percy has this natural fear against him at least subconsciously but is also very suprised when Paul doesn't get at all angry over the dent. It's such a sweet moment for Percy; he gets to learn how good fathers are.
3.
You mentioned gambling and drinking. Percy shows great dislike for the game in book 1, but he is forced to play cause of Dionysus. He's relatively good at it but doesn't play because he associates the game with Gabe. Same for alcohol. There's a line in the book where Percy says he knows how to recognize when others have been drinking or, as Percy calls it, hitting the happy juice. Obviously, alcohol makes Percy uncomfortable in itself, and he immediately dislikes Dionysus because he is a drunkard and a poker player along with a build similar to Gabe, which makes Percy naturally dislike him greatly. It doesn't help that Dionysus is a complete asshole but his initial natural dislike of Mr. D is due to Gabe.
4.
We all joke about how Percy is a fugitive and known terrorist in tons of states. This is all Gabe's fault. Percy gets in such problems with the law all due to Gabe and how he set literally every police department possible on Percy's trail. Now Percy, being Percy, he manipulates the officers to get on their good side, but he obviously still has problems with the law due to this entire fiasco.
The fandom likes to say that Percy got all his dark aura after Tartarus, but Percy has literally had killing intent since he was 12. One of his first lines in the book is "I am going to kill her" in reference to Nancy Bobofit. He gets gut punched by the realization that Gabe has been hitting his Mom. Gabe literally raised his hand against Sally in front of Percy in book 1. You can't tell me Percy recovered from that. He thinks then too of pulling Riptide and killing Gabe but realizes it wouldn't work on Gabe. Now Percy, who almost always means exactly what he says when talking to people, calls Gabe 'human by the loosest definition.' A 12 year old thinks that you can imagine how bad the situation was.
After Book 1, Rick heavily avoids mentioning abuse in his book cause he is trying to write for kids, but it shows.
Percy thinks of Gabe when he first accidentally iris messages in on one of his Mom's and Paul's dates. Percy is immediately suspicious, which is obviously why Sally hadn't told him anything before this. She wasn't completely sure about Paul, and she also didn't want Percy to worry. When Percy sees her laugh with Paul, he thinks of how much trouble his Mom went through with Gabe.
This is important because after Book 1 when Percy finally learns why Sally kept Gabe around in his head he twists the narrative as his Mom suffered Gabe, not that both he and Sally but only Sally suffered Gabe and why? To protect him. He BLAMES himself for something that's obviously completely not his fault. But in his head, he ends up masking his own pain and considering only Sally's pain valid. This is why Percy doesn't talk to anyone about Gabe and also why everyone thinks Gabe was a bit of a jerk but not an abuser. We literally see PERCY DO THIS TO HIMSELF. Same thing in The Last Olympian. Same thing in Mark of Athena. He talks about how his Mom suffered by staying in the awful marriage, not about himself.
5.
Now the famous House of Hades scene. See Tartarus draws out negative emotions and experiences and worst nightmares of a person to feast on. This is very telling because despite the endless life-death situations Percy has been in ,he thinks of Gabe. Because to Percy, self suffering is no suffering at all. But his Mom suffering is the worst of all. Now Annabeth obviously doesn't get the cue because she has no idea about how Percy lived in his past. While it is true that Annabeth cannot be held responsible for not getting why Percy brought up Gabe in Tartarus and took it as Percy making a joke; a case can be made against Annabeth's lack of initiative to learn more about Percy's life before all this. I digress as that's a completely different discussion. Point stands is that Percy is so unbelievably broken yet loyal that he doesn't even consider his own pain valid.
The next mention of Gabe is directly in Chalice of the Gods. Percy rather openly thinks how much he hated family dinners with Gabe. Also, he has a very nice conversation with Sally soon after he recovers from being turned into a child, where he talks about how powerless being a child felt and how afraid he was. I am certain that the implications indicate at both monsters and Gabe and how a young Percy had been very afraid of both situations but more of Gabe than monsters. Go figure.
It's plenty clear how much trauma Percy has from Gabe and how much he has trained his mind to either avoid it or redirect it elsewhere lest he regress into bitterness and anger issues.
It's probably longer than you expected, but I like systematic exploration of points, hence the long rant. I have done my best to break it down, so it's easier to follow. Also, I am very, very happy for this ask as I really love to explore Percy's personality and Percy's powers. Feel free to send me more along this line of thought.
@fourcornersofcreation ,@hermesmyplatonicbeloved, @helenofsparta2 , @ogjacksonsimp, and @berrybore have all also made posts exploring some of Percy's trauma and they will probably have things to add as well. So please check their posts on this topic as well in case I missed anything.