I've read this fic once before on Archive of Our Own but can't find it now.
It's about Draco being a slave and about to be sold when the Aurors come to arrest them and Ron is there too. And then while the other slaves have been taken home by their family Draco still stays at the Mungo's. Ron comes to the Grimmauld Place and tells Harry about this, who decides to take Draco home with him. And the next forward is about Harry helping him to be better.
I may have confused the following with another story, but I remember Ron and Hermione being married with two children and coming to see Harry and Draco for dinner, with Draco still being on guard?