I just read this on my Kindle, but it seems like AO3 is down so I can't leave feedback there.

I really, really loved this. I really love this in how difficult it is between the two of them, how imperfect and painful it can be. I also really love the sense of history, of aging, that it comes with this whole story, the way they're forced to become parents to these students. It feels as epic as their canon relationship, and that's pretty amazing.