This Cold Year ― Percy Jackson & Annabeth Chase²

the future

With Jason's help, Naomi, Percy, and Annabeth erect shrines for Erebus, Bob, and Damasen at Camp Half-Blood, so they'll never be forgotten. 

Naomi gets a bachelor's degree in psychology and education from New Rome University and a master's in school counseling from a university in New York. Annabeth gets a bachelor's degree in architecture and environmental design and a master's degree in architecture. Percy gets a bachelor's degree in social work (social worker Percy just makes so much sense to me).

After getting her master's, Naomi (with the help of the gods and quite a few other demigods) opens up a boarding school for demigods and legacies. The first school is built in New York and after a few years another is built in San Francisco; Annabeth designed both campuses. Naomi is the school psychologist, and Percy refers any demigod/legacy clients to the school. 

(And Isaac ends up becoming a history teacher at the California school.)

Naercabeth (still workshopping the name) never get legally married, partly because poly marriages aren't legal and partly because they don't trust Hera to not screw up their relationship (again) if they get officially married. They do have a ceremony, though, and exchange rings and vows in front of all of their friends and families.

They settle in a small town in New York state, less than an hour from Sally and Paul. When the Argo II crew and their friends and family get together every few years, their house (built by Annabeth, of course) is the meeting place. 

(They have an entire forest as their backyard, so Mrs. O'Leary, Skia, and a hyper rescue named Mags have plenty of room to play.)

They end up having 3 kids: Lila, Maisie, and Rafael. Lila takes after Annabeth's personality but is way more impulsive (just like her dad). Maisie is quiet like Naomi but once you get to know her she can talk for hours. Rafael is like Percy's clone personality-wise (super loyal, total mamas' boy, & chronically sarcastic). Lila inherits Naomi's plant/flower powers, Maisie inherits the earthquake side of Percy's powers, and Rafael can control shadows (from being a son of Nyx). 

(Teaching Rafael how to control his shadow powers helps Naomi finally heal from the loss of her own.)

Rafael decides to join the Twelfth Legion Fulminata at eighteen (Frank and Hazel brought a lot of reform to how the legion is run, starting with raising the age requirement and making it a voluntary service rather than a required one, because child soldiers ain't it!) and becomes praetor at twenty-one (fourth-generation baby!).

Lila is a Camp Half-Blood kid through and through, and she stays in the Poseidon cabin when she's there. She's an honorary Cabin Four kid, too (just like her mom). When she ages out, she goes to college for psychology (again, just like her mom) and becomes a trauma counselor, specializing in working with demigods & legacies.

Maisie ends up joining the Hunters of Artemis at seventeen, after a full year of discussing it with her parents and deciding if it's really what she wants. Aunt Thalia is thrilled and takes her under her wing immediately. 

Grandpa Gabriel lives long enough to see his great-grandkids start school and dies in his sleep shortly after. He gets a full military funeral, and he's buried between his wife and his son's empty grave. 

(He fills Ben and Nomi in on all of Naomi's adventures when he reaches Elysium.)

Naomi, Annabeth, and Percy don't go for rebirth for a hundred years, spending that time with each other and their loved ones in Elysium and taking a well-deserved vacation. When they do go for rebirth, they find each other and fall in love all over again. 

(That's their third life, and they reach the Isles of the Blest together.)