PJO/HOO headcanon (takes place in a world with no ToA): Chaotic Good Primordials
-Chaos occasionally goes where they wants, so they occasionally watches the demigods go on their quests and records every time they unintentionally unleash chaos by facing monsters (Percy is his favorite since Mt. Saint Helens). They manifested into a woman to Sally Jackson to hang out as friends and in a surprisingly butterfly effect, Chaos suddenly is godfather/godmother of Estelle Jackson (Which obviously even Chaos themselves didn't expect at all).
-Lady Nyx adopted demigods who have accidentally fallen into Tartarus, in fact, the process is: She scares them to death in her 40ft tall form -> when the demigod is about to faint, she and her children start laughing and become more or less human-sized and calm him down (it's a freak them out tradition) -> Previously adopted demigods usually wait for the whole act to be over and have dinner with the potential new little brother/sister. (Percy and Annabeth were almost adopted that day.)
-Tartarus couldn't really care less about Gaea's new attempt to try and dethrone Olympus, although he supports her because if there's even a slight chance of bringing the Big Three back down to his domain, he'd do it without hesitation. Despite apparently being angry with Damasen in their confrontation, when Percy and Annabeth leave he pats Damasen in the head and walks away.
Extra fact: After Blood Of Olympus, Tartarus gives Daedalus' laptop and Annabeth's dagger to Eris and she (remember that in Sea of Monsters it's implied that she works with Hermes) sends both things to Annabeth.
-Uranus stayed living in the old mount Othrys in Greece (there are versions of the myths where it is said that he is alive, and he is the one who advised Zeus to eat Metis if he did not want to be dethroned + he also helped in the first Gigantomachy). The primordials (except Gaea) visit him from time to time. The constellations? well, they live there, Zoe is obviously very confused that at one moment she was dying and in another she is in Greece with this primordial who should be dead being her new Father. After speaking against Zeus and defending Apollo, Uranus gave Jason his blessing and protection.
-Lady Hemera and Lord Aether regularly spent time at Camp Half-Blood before World War II, after the Giant War they both basically manifested a cabin, lifted Mr. D's punishment, and are basically the de facto camp directors and surrogate parents to those with no family in the mortal world and most of demigods since many were unclaimed for years (and despite being claimed many still choosed Hemera and Aether.)
-Pontus and Thalassa woke up after the second titan war and the first thing they did was take Oceanus and Poseidon by the ear (Even if they're not their father, they treat them like their children). In this timeline ToA doesn't happen, but Percy having to do chores for Zeus and other gods does, Poseidon rambles about it during a dinner at his palace and Pontus promptly jets off to Olympus to have a diplomatic chat with Zeus (no one messes with a child of the sea) while Thalassa do a Tea party with Aphrodite.
-After the war, Gaea appears in the mansion of the Night by the work of Chaos, there is basically a divine intervention and a lot of therapy in between (+Chaos is now a godfather/godmother, he would not allow under any circumstances that a war would harm his goddaughter) After a while, Chaos hands over dominion of Ogygia to Gaea, and she and Calypso make the island a Paradise, and when Leo arrives both are beyond confused on how and why (btw, Leo and Calypso have free pass to go back the island after they leave)
Gaea easily could leave, but choose to stay and work in the island, she doesn't know why or how, but soon, Metis, Helios, Selene, Pan appear there too, and she look fowards to the day she can see her children again.
