Gabriel makes everything musical*
Dean is a demon and with Ann Marie and she is also evil but fascinated with Dean. Who doesn't seem to mind her following him around everywhere he actually quite likes it.
They form a bond (a little more than just a bond). Sam, and Cas find Dean and try to get him back. They find him with Ann Marie. Both confused and Cas seemingly upset. They try to get Dean to come with them but he will not listen. They start an argument and ask who the hell is that chick!?
"She's with me" Dean replies and she smiles Devilishly while slightly blushing.
Cas angered and perturbed by this filled with many raging emotions far too many to get out at once SUDDENLY *LOVE, love will keep us together, think of me babe when some sweet girl comes along singing a song you just gotta be strong* * He is suddenly singing and dancing and looks very terrified while doing it. Sam and Dean look at each other at the same time confused as hell. *JUST STOP CAUSE I REALLY LOVE YOU* *STOP, I'VE BEEN THINKING OF YOU* LOOK INTO MY HEAR AND LET LOVE KEEP US TOGEEETHER* music actually playing as Cas sings a song to Dean and dances kinda like a ballerina. before they realize it they are all dancing to Cas's song. Cas takes Dean and dances with him and Sam and Ann Marie are back up dancing. All of them with petrified looks on their faces but can't stop. *I said it before and I'll say it again* *while others pretend I need you now and I'll need you then* Cas sings as he gets closer to Dean. Close enough to have their bodies pressed up against each other as they dance to the beat *dahh dada daa daa* Sam dancing in the background like an over large moose dork and Ann Marie just keeping to the beat like normal dancing. *look in my heart and let love..KEEP us togetherrr* as Cas places his hands on Deans face and pulls him in for a kiss then pulls away *whatever*. Dean still forcefully moving his feet to the beat but utterly shocked and just staring off. *I WILL I WILL I WILLL* As Cas moves over to Ann Marie and STABS HER killing her dead. (haha bad grammar joke). *daaa dada da daaa dada daa daa*. She dies as the song ends. Cas, Sam, and Dean just stare at each other not able to move scared, confused, violated, and just feeling wrong.
(later after all the singing Gabriel shows up and laughs his ass off at them)