Characters involved: Ron, Hermione, Harry, Ginny, the other Weasleys, healer
Mood of plot bunny: sad but romantic. lots of family bonding and loads of crying (mainly Hermione)
Plot line: So Ron and Harry are just starting their new jobs as Aurors and so far they haven't had any big jobs. That is until their boss (who kinda hates them) tells them they are to follow a former Death Eater and capture him once they know he is up to no good. On the job they realize who it is. Augustus Rookwood. He's the one who killed Fred and naturally Ron wants revenge. He charges out and end up killing Rookwood but nearly killing himself as well.
Skip to St Mungo's. The Weasley, Harry and Hermione are there. Nobody knows how Ron is. Hermione runs off and is talking to herself. She realizes she does love Ron. (They weren't really dating but they both had feelings for each other.)
This is where I always get stuck. The ending can be whatever you want. Just make sure Ron and Hermione get together.
Other details: Harry and Ginny are together but not married. Hermione and Ginny were still at Hogwarts and were quickly sent to St Mungo's after they heard what happened. I imagined this as a short story. Not a oneshot but not really long either. I was thinking somewhere between 5 and 10 chapters? But you can do whatever you like.
Take good care of my bunny. She likes to be worked on often. Can't wait to see what you do with her! Good luck.