Okay I searched through the homeless tag and can't find this story at all so...
I don't remember much, but for some reason I think all 4 of the boys were homeless. I know Brendon got kicked out, and I think Ryan/Spencer ran away. Jon's circumstance had something to do with Tom I thought, about a break up or death but I'm not positive.
I'm fairly sure they lose Ryan along the way or something and Spencer gets mad and I remember a scene where they're driving in a car and it's Spencer, Jon and Brendon and Jon kicks Brendon out of the car and Brendon just goes. Then Spencer looks at him and just says something along the lines of "His parents kicked him out" and Jon says "Fuck" and I think they go search for him.
It had a happy ending, I remember that, and I'm CRAVING this fic so hard and if you can help, I'll worship you.
It isn't this fic (
http://archiveofourown.org/works/82541) but that fic is what reminded me of it, so I think they're similar.