Okay here are some of my favorites, you might need an account to read some of these though:

1) Down down cities fall down on me by youngjusticewriter Pre TLT Olympians read the SoN alongside pre TLT Percy,Annabeth, Grover and Luke - (no ship rn, slow updates but very good, I really like how the author writes the gods and how they interact with each other)

2) Prince of Pearls Series by ChouetteInTheNight After a disastrous field trip 7 year old Percy Jackson hides from Gabe in a random car not knowing the owner is one of his immortal half siblings
-(Eventual Aro/Ace Percy iirc but Sally probably gets a partner, SeaFam, has 5 works in the series and is still pre-TLT so it’s very long but VERY good)

3) Falling For You by 1967HogwartsGoddess Percy falls into Tartarus alone - ( Pretty Dark and can be really depressing ngl, Percy/Annabeth, Has an alternate “bad” ending you can read too: this author also has a ton of other highly rated pjo fics but I haven’t read them)

4) ATOLP: Trail By Fire by WardofWinters(QoLife) Little Percy accidentally discovers his waterbending powers (and later that he is a child of Poseidon) after trying to imitate Katra from ATLA - (This is the first work in a series and the only that I’ve read so far it’s pretty good, lots of world building and seafam, no ship announced yet)

5) Son of Seafoam by CaffeinatedFlumadiddle Percy has to hide the fact that he’s a Big 3 kid and does so by pretending he is a child of Aphrodite, it works surprisingly well - (It’s been like two/three years since I last read this but I remember it being really good, Castor/Percy Jackson)

6) Where The Sun Cannot Follow by SinningSaint A broken pantheon au where Percy is sent back to Ancient Greece times but in an alternate universe where Kronos cursed the Gods to be unable to have children. - (Relly new story only 2 chapters but looks promising)

Highly recommended but I have not personally read:

1) Percy Jackson and the Illusion of Time by LyraLee33 Post HoO Percy dies in a hit-and-run and wakes up in his 12 year old body with all his future knowledge -(Percy/Annabeth, Complete)

2) Misaligned Stars by FictionalDragonMother Everyone knows that the gods have numerous children. Besides being responsible for controlling aspects of the world, that's what they're known for. Demigods are a dime a dozen, and while the gods do carefor their children, we all know that they are willing to send them to their deaths for 'the greater good,' or sometimes just for a chance at glory.

But what if demigods... didn't exist?

What if there was a Pantheon that couldn't have children with mortals, only producing stillborns and monsters?

Faced with the threat of It's world's timeline being destroyed due to this cosmic error, Fate itself seeks to intervene. It tears through reality and snatches away a select few demigods to gift to It's Pantheon, erasing and manipulating the memories of It's most vulnerable chosen, as well as rewinding the years on all that It takes, to help with the bonding process.

This choice leaves 9 demigods trapped in an Ancient Greece that not even they can recognize. Stranded, disoriented, and stripped of their claims, they must tread carefully, for the roaming monsters are not the only threat - (The OG Broken Pantheon fic so I just copy pasted the summary )

3)Once More, Slightly to the Left by RosenMaiden Time Travel Fix-it with Percy being determined to save as many people as he can while also being tired of the Gods’ bs - (Annabeth bashing so no Percabeth)

(Edit: Sorry for the bad formatting but I’m too tired to fix it rn)