Okay I think I've finally settled on a heritage for Percy and pretty much most of the characters I've mentioned that aren't Thalia or Nico.
Percy - I've decided Percy is going to be the Son of Poseidon and Juno now before I get roasted hear me out lol.
Percy isn't Juno's child in a traditional sense but more like how Jason was Juno's champion but a bit more than that.
After Percy was born, Sally ended up praying for protection for him to basically any goddess that would listen as she sort of knew he'd lead a more tragic life than others and Juno ended up listening and embedded some of her essence in him, sort of like a blessing and Juno basically just adopted him (especially after Sally dies in this AU because I'm evil like that).
But similar to Jason in canon, Percy doesn't really meet Juno, but he does meet Hera which is a bit more prone to disliking him but doesn't like outright hate him. She's kinda just thinking "why embed my power in a son of POSEIDON?? What were you thinking Juno" but like by the end Hera definitely comes around.
He'd also be a legacy of Sol like in my original plans but he wouldn't really get any major insane abilities out of it, if he did maybe something to do with light but I'm not sure I could link light to his water, storm, and air (from Juno) related powers properly so I might not touch that...
Gabe Ugliano is still a thing. I say this because I feel like its a big part of his character because some big parts of his character is his low self esteem, his loyalty, his anger, and I feel like some of the bigger and even smaller parts about his character (possibly) stem from his circumstances and how he was raised, especially in TLT. So I'm opting to keep him in here.
Percy at the beginning would have twice the enemies. Not only is Hades after him, but Zeus is too (because of the Juno thing) so when Percy fights the minotaur even with Hades intentions to save Sally as a bargaining chip, Zeus intervenes and so Sally ends up dying against the Minotaur.
So Percy ends up with his only friend, Grover by his side. And in this timeline there's no Annabeth so while he's at camp and especially after his claiming he's alone. He still goes on the quest and doesn't save his mother but he does retrieve the helm and master bolt because it's what his mom would've wanted him to do- to help.
Percy does go back home (and he does kill Gabe Ugliano because he deserves way worse than being frozen as a statue). And from there he becomes a year round camper because he has nobody to go back to, he didn't really have any friends or family so he's all alone.
Eventually I'd say he does meet Paul through Rachel and finally deciding to go home after the labyrinth and a few mist trickery things later ends up going to Goode because of Rachel and meets Paul and Paul basically ends up adopting him at some point (and also Fredrick Chase after meeting Annabeth and then her dad).
Annabeth - Annabeth would be after thinking hard and long about it a Roman child of Apollo. She'd go a long time thinking that she just didn't have powers until she finally comes in contact with the Romans (yeah I read a Roman!Annabeth story and got this idea so yeah). I also don't think she'd run away in this timeline, especially because the baby was intentional (and also because she's a legacy of Athena.) Freddy would be a good parent in this timeline and take care of his daughter lol. So in this timeline she doesn't meet Thalia AND Luke but possibly one of them.
I think Freddy would be similar to Sally and just wanting to keep his daughter as long as possible, so he and her would make a lot of trips to camp half-blood when Annabeth was younger during the summers and weekends, sort of like trips for certain periods of time. Freddy being of demigod heritage himself wouldn't want Annabeth to be at camp half-blood, especially knowing that Chiron sends KIDS on quests (Fredrick might've been at CHB once, got sent on a quest when he was younger and he was the only one who survived and never went on one again and left it behind as soon as he turned 18) so his home would be equipped with Celestial Bronze weapons. Freddy sometimes would get too caught up in Annabeth's safety that Annabeth feels more so trapped and guarded from every little thing which would lead to Annabeth running away after an argument about a monster attack which would lead to Lupa finding her.
Freddy is eventually put in the loop about where Annabeth is: Camp Jupiter and despite everything, she becomes a child soldier anyways. But Annabeth being at CJ is the best thing ever. All of a sudden she has all these cool powers (which I want to go more in depth about in another post) and she's living her dream, she's always wanted to fight, always wanted a quest. But eventually she finds out it isn't as hyped as it's made out to be and decides to simply come back home because even though he handled it in a bad way, she finally understands why he kept her away from CHB and from fighting monsters.
Thalia - Thalia's backstory is pretty similar to canon. She's the daughter of Zeus, but the daughter of two different aspects, the chthonic earth Zeus (which was a version of Zeus in certain parts of Greece, and also plays a part in her fear of her air powers) and God of Storms and Lightning Zeus so she's way more dangerous. She comes from a pagan family and Beryl was a huge worshipper and legacy of Aphrodite.
Thalia runs away and meets Luke like in canon but doesn't meet Annabeth. They end up getting to camp but shit hits the fan when Luke is sent on a quest. Luke is excited, really excited he can finally prove his worth and get the campers to trust him but only Thalia comes back (with the apples) but no Luke, no other demigod comes back.
But Thalia is different now. Besides the scar etched on her face like a painful reminder somethings changed. She's much more volatile and dangerous to be around. She also doesn't seem to age much either, she doesn't really grow- not really. After she reaches 15 she sort of just stops, like she's stuck in time and nobody thinks about it- not really. Percy comes to camp and Thalia teaches him. She tutors him the best she can, along with trying to steer his way of thinking. She stays at camp until the end of summer, where at the end she tries to kill Percy (she's been trying to hold on as long as possible and convince him, she doesn't want to hurt Percy, not really but Kronos is offering her power and a world where kids don't have to go on quests ever again. And if Kronos has to coerce her into killing a kid so be it).
Luke - Luke, the son of Hades. Luke who's mother was driven insane when Hades offered her godhood, Luke's mother who couldn't handle the power of the underworld and is slowly withering away, so he ran away. Luke is similar to Nico (in TTC) when he finds out what he is though, he gets to have a purpose and life and he free from his mom, and Thalia is an added bonus he likes very much.
Luke is nearly 16 when he's offered his quest and readily accepts (I aged him down a bit to fit my insane story) but he dies- or he thinks so. He's swallowed by the Earth and next thing he knows he wakes up and everything's different.
Thalia is gone and there's this guy named Percy? And he comes back to camp and after finding out what happened suddenly everything's too much. The attention and expectations were easier because Thalia carried them with him. But now she's gone and suddenly everything's up to him. Percy tries to help and grows closer to him and Luke cant help himself, he reminds him too much of Thalia. But Thalia makes him an offer and Luke can't bring himself to refuse. Thalia was always Luke's everything and if he becomes the villain everyone at camp was expecting him to be then so be it, right?
Clarisse - Daughter of Nike (Legacy of Glaucus). Clarisse being raised in a militaristic home, being from a lineage which is basically all military soldiers and demigods, being pushed to be the best- to win. Clarisse had always known she was a demigod since like- forever and so ever since she could remember she's been molded, training, fighting even in the smallest of ways like withholding emotions and being trained in weaponry.
She's eventually found by Coach Hedge however and taken to CHB. She doesn't get claimed until after SOM where once she comes back with the fleece she's claimed by Nike and Glaucus (Glaucus would be the one who gave her the boat in this AU and the warriors are simply dead navy men.) Clarisse doesn't join the titan army even though she's tempted at times, because she knows Percy will lead CHB to victory.
Their relationship doesn't start as hostile but definitely slowly grows hostile overtime. Clarisse has been training her entire life for this life, but Percy gets most of the quests, he leads the quests and sometimes does stupid things that don't lead to victory. Clarisse's fatal flaw, hubris gets the better of her and eventually their conflict comes to a head and the camp becomes divided but eventually they talk and reconcile. She finds out they're more alike than they think, and that he's just a kid and she learns that she's just a kid too and she decides he'll bring this kid victory, that he'll rage and fight for him.
I've been writing this for like an hour but this is part one, not everyone's going to get a godly parent swap but I just wanted to go over some basic characters for this one so uh enjoy. Next post will prob be more god swap stuff, either other parentages or going into depth about these (five?) and their powers.