So, it's Real People Fiction (I can't recall if it was slash or not; I don't think it was) and it's set in a post-apocalypse (I think zombies; the settlement/camp reminded me of The Walking Dead).
It had a rather wistful/sad tone to it.
Starts out with Jensen's POV and nobody knows he used to be an actor on a show called Supernatural, although I think someone realizes he's the model on a burnt/destroyed billboard watch advertisement. He's like "that was a long time ago" or something. You also find out his family perished during the outbreak & he's just pretty miserable/unsure why he's even still trying to stay alive.
Scouts of his camp/settlement alert everyone there's a band of survivors approaching, and Jensen always hopes/prays it's someone he knows.
I'm pretty sure the climax of the story is just that the band of survivors includes Jared Padalecki (whose family also perished) and they hug it out & cry.
There might be a little
bit more after that... describing how meeting each other pulled them both back from the edge & became more personable with others as well as better contributors to the community, but I think that's it.
It was pretty short, but the scene where Jensen recognizes Jared was friggin great. I'd love to give it a reread.
Also, after checking with /r/fandomnatural on Reddit, it seems like When the World Ends; That Is When We Begin by TruelyEsoteric
might be the fic I'm thinking of, but the details seem off: Jared was alone when he arrived at the camp, Jensen didn't have a surrogate daughter, & I don't think it was slash.
Thank you so much for any/all help on this!