This is Raven Cycle fanfiction that takes place ~5 years after the end of the final book and primarily follows Adam and Ronan.
When I tell you that this destroys me every time I read it I am being so, so serious with you. Yes, it is fanfiction, but it is also so notorious in my friend group that it is lovingly known and referred to only as "The fic". The one fic to rule them all. And collectively, we've read a lot of fic so that's actually saying something.