I don't remember much about it save that it was likely a crack!fic and talked about the Marauders from Snape's pov. They were apparently evil (of course, seeing as it was from Snape's pov) and had transfigured Snape's pet dog or wolf pup or some such into Remus Lupin. Snape even rages that Remus Lupin is so obviously a made up name because it's pretty much wolf wolf masquerading as a real name. I think they also use an engorgio on a small squid and throw it at Snape, giving that as an origin story for the giant squid.

I think I read it around 5 - 6 years ago on ff.net.

 

Not this one, no. I distinctly remember that one being a bit of a crack!fic. But thanks anyway Ched.