Stories where the seme knows something about the uke that no one else does... if that make...

https://www.mangago.me/read-manga/incidentally_living_together/

like blackmail or childhood friends/the uke told him out of trust

Ah, not really, an example would be the seme finding out the uke is secretly an otaku or something like that, a secret no one was supposed to know about, but not blackmail
(づ￣ ³￣)づ

Thanks for the rec ヾ(❀╹◡╹)ﾉ~

https://www.mangago.me/read-manga/idol_kun_wa_koi_wo_shiranai/ uke is an idol