i've never heard of this kind of thing before (if i have, i've forgotten all about it). it sounds awesome. :)

Fandom: Harry Potter
Pairing (s): Teddy/James
Most Popular: I think Here Now, Gone Yesterday (or Back to the Future) (AO3) ~21k
Warnings: None (has Remus/Sirius on the side)
Personal Favourite: Both the above and Fragments of a Life (AO3) ~5k
Pairing (s): Teddy/James
Warnings: Heavily features James/OC but endgame is Teddy/James


Pairing (s): Remus/Sirius
Most Popular: Probably the House of Love series, consisting of the prequel House of Cards and then House of Love. ~86k in total. (not recommended to read this on ao3 due to formatting issues.)
Warnings: none really, but there are lots of OCs in sexy situations with our boys
Personal Favourite: without a doubt Indiana Lupin ~67k
Pairing (s): Remus/Sirius
Warnings: none


Fandom: Avengers and related
Most Popular: Definitely How to become a Superhero and gain a family (minus the picket fence) (AO3). This one crossed the 10k hits mark on ao3 a few weeks ago, which no other fics of mine have done. ~7-8k
Pairing (s): Tony/Steve & Tony & Bruce Wayne
Warnings: none
Personal Favourite: He Eats Snow For Breakfast ~25k
Pairing (s): genfic but somewhat Loki-centric, with Natasha/Pepper prominently, Phil/Clint background and pre-romance/slash Tony/Steve.
Warnings: severe injuries at the beginning of the fic (blood) and mentions of torture


These are the ones of mine I can think of off the top of my head. :)