Thanks for the mention of Scissors <3. You might have seen these, then, but both feature a possessive and needy/loving Lucifer, and a Sam who is not (at least at first) interested:

A Young Writer Marked for Death (http://archiveofourown.org/works/2439464) (58K)
Summary: Being an aspiring writer in Paris isn't easy, and with Adam wasting away from consumption, Sam's life sure is difficult. It could be worse, though: Adam could be dead or they could both be back in Kansas where they would end up in jail. Monsieur Lucifer could have asked them to leave Le Cabaret Perdu when he discovered the less than flattering poem that Adam wrote about him. Instead Sam makes a surprising deal with Lucifer that is going to change Adam's life — and his own.

The Temptation of Sam Winchester (http://archiveofourown.org/works/606821) (30K)
Summary: Sam is doing time in Hell, Detroit's new, experimental prison. Caught in the battle between rivaling gangs, Sam finds out exactly how brutal prison life can be. To survive, Sam must make the choice between two gang leaders, the cruel Crowley and the ruthless Lucifer. Lucifer, however, is the master of alluring offers, and soon Sam finds himself falling into temptation.