Devil's Arcade (https://www.fanfiction.net/s/4718216/1/Devil-s-Arcade) by Zubeneschamali
S4. While still dealing with the aftermath of the wishing well, Sam and Dean are taken by a group of hunters who will stop at nothing to find out the truth about Sam's abilities and how Dean managed to come back from the dead.

Land of the Lost (https://www.fanfiction.net/s/9466096/1/Land-of-the-Lost) by K Hanna Korossy
S5. Hunters tend to see things others don't. It was just a matter of time before some of them pieced together who let Lucifer out.

There's also 5X03 and 5X04 episode-linked fics like Idiot's Paradise (https://www.fanfiction.net/s/5409251/1/Idiots_Paradise) by Phx that deal with Sam being hunted down by other hunters, if you're interested.