Sam and Dean were in Las Vegas and on the hunt for a siren. Their intel had led them into a nightclub, but it didn't take long for the tables to turn and for the hunters to become hunted. The siren had them under their charm.

Much to their luck, there wasn't only one siren in this place. As soon as the second one noticed what was going on, they went up to them, working their magic to distract the two brothers. "hey, boys, you wanna come with me?" they asked them, leading them to their flat.

It was a panic response, really, a try not to have them get hurt, and now they had two complete strangers in their bed, sleeping on their couch themselve.

The next morning, they woke up early, rummaging through their kitchen to mix up a potion to free the two strangers from the siren's spell put on them. But the moment they were putting the ingredients together, they felt a knife on their throat. "Don't move." Dean told them, sounding rather angry.