I have something for you
for whatever reason you want Maekar is a forgotten prince and then he presented as omega at way too young age so he ends up in maiden vault an with things going on the family forgotten about him until some crisis come and then he's out only to marry Baelor
well, in the light of recent asks I think I might have something for you (Maekar being a bastard of Daeron II and Daemon Blackfyre -> here)
so, Daeron and Myriah claim Maekar as their own child but they never bond with him because of his origins, the only one that tried was Baelor BUT that soon ended as he was taken by his responsibilities as an heir
soon, Maekar is raised more by septas and nannies instead of his family, soon growing to kinda resent old ladies that take care of him because they allowed themselves to be harsh with him, verbally and physically (no one bats an eye, especially after he's allowed onto training grounds)
the distance grows, and soon some people forget there was a fourth prince, that's how little he's present in the court
naturally, he still tries to get a bit of affection, at least from his brothers, so he's Baelor's little shadow on the training grounds, he's sneaking out to library where Aerys is, or goes to the gardens where Rhaegel loves to play (after that he's always getting scolded by his Septa, often getting his back whipped)
and then, at barely age of 12, Maekar presents as an omega and surprisingly he's not that mad about it (he would often read that royal omegas were supposed to be loved and protected, a childhood fantasy that gave him hope that now his life will take a new turn for the better)
Daeron and Myriah are scared because, well, Maekar is also Daemon's son. Daemon presented at similar age. Daemon forced himself in Daeron's bed, drugging him, which caused in Maekar being born. they don't want the history to repeat itself, especially when they see how Maekar is often following their sons, mostly their perfect Baelor
so they make this tough decision to lock Maekar up in the Maidenvault (they say it's for his safety, that he's too young, that they don't want any alpha to put their hands on Maekar. and he desperately wants to believe that they care, that they do it out of love, not because he's a burden)
and so, he's locked up, with one trusted servant and his old Septa visiting him. Maekar hopes it's just temporary, but as days turn into weeks and his family still didn't visit him, deep down he knows the truth (he only knows it's his nameday because of the maid who keeps tending to him, and soon they grow closer, almost like friends)
Maekar grows up stubborn and full of resentment, always with the same people around him, always in his tower
until the rumors of a Rebellion stirring up reach King Daeron
Daemon has no real claim, he's not only a bastard, but also an omega, and yet he's trying something. but, instead of going to a war right away, they meet on a neutral ground to negotiate, and soon they reach an agreement
Baelor will marry Maekar
thanks to that, Daemon's own flesh and blood will sit on the Throne one day (it's either that or the whole Kingdom will know that Daeron was tricked by his younger omega brother, and that the youngest prince is actually a bastard. it would harm people's trust to the crown)
and so, after years of isolation, Maekar is suddenly out of the Maidenvault, only to marry his brother and give him heirs
and you know what? he's not happy about it at all (at least not yet)
