Seconding "A Habit Hard to Break," it's good stuff even though the pacing is glacial.
I don't know if it's quite what you're looking for but my other favorite fanfic is "Dragon Kick Your Butt Across The Multiverse." The premise is pretty campy, and it more or less starts out that way, but it's well written regardless, and then it starts taking itself more seriously and shit hits the fan fast and hard.
Characterization is mostly very solid which in my opinion is the most important thing. And the author both updates often and puts out a lot of content; the fic isn't even 3 months old and it already has over 30 chapters and is fast approaching 200k words.
Kind of like the show, give it a chance and look past some of the sillier stuff and it's more than worth your time.