A long, long fanfic full of scorching hot wincest. This would work better as two books imo. The first half is a plotted hunting fic and the second half is Dean's detailed kink mapping of Sam.
Manip by TravellerInTime74
'They are cliche codependent, they will never love anyone like they love each other, they are so deeply ingrained that Sam believes Dean when he says there is nothing Sam could do that would make Dean leave. Sam believes him. Sam feels the same way.
They are both so fucked up, so very fucked up, that yeah, this could be bad, but even if it doesn't work, it probably won't make the fucked up any worse.'