In Heart, the brothers followed the news of human bodies lacking hearts found dead in and around San Francisco, CA, each of them killed in the week leading up to the full moon. They recognized the modus operandi of a werewolf, much to the delight of Dean, who knew how to kill them and was invigorated by encountering the first werewolf the boys had found since they were kids hunting with their Dad – and wouldn’t we all like to know more about that hunt?
The latest victim was a lawyer, and the woman who found him – his assistant, Madison – proved to be lovely, intelligent, independent, and irresistible to Sam. While Dean tracked her creepy, stalker ex-boyfriend, Sam kept Madison chaste company, while harboring anything but chaste thoughts. And then things went south as only Supernatural could route them, via the horror GPS: after Madison had retired to her bedroom to sleep, the ex-boyfriend was killed by the werewolf, and Dean recognized the killer as Madison, transformed, and managed to slash her arm with a silver knife before she knocked him out. When he came to, he warned Sam, who had been unaware of Madison’s escape and return, but then imprisoned Madison in her own apartment.
And that’s when things twisted back on themselves yet again. While Dean maintained that they had only one choice – to kill Madison before she killed again – Sam recognized her parallel to his own situation, as someone with an evil part that she couldn’t control and of which she wasn’t even aware, and threw it in Dean’s face: So me you won’t kill, but her you’re just gonna blow away?. He challenged Dean to risk the possible cure suggested in John’s journal – severing the werewolf bloodline by killing the were who had turned Madison – while he kept Madison secured. At Sam’s desperate urging – Dean, I need you to go out there. At least look for the thing. Dean, we can save this girl! – Dean hunted the werewolf’s territory and successfully took him down. He turned out to be her sweetly solicitous neighbor Glenn, who reverted to human as he died and revealed that he had no clue about his killer werewolf side. Sam, meanwhile, saw Madison transform, but managed to lock her in a room where she could do no more than claw the walls to shreds until dawn brought her back to human.
Thinking everything resolved, the brothers watched her through one more sleepless night, and when she didn’t transform again, believed her cured. Dean read the signs and moved out of the way, and Sam and Madison gave in to their mutual attraction and slept together – and Madison transformed in the night and went hunting, to Sam’s horrified dismay. Come morning, finding herself in a place she didn’t recognize, she called for help, and realizing that what they had told her was the truth – that she was a werewolf, as mad as that had to sound – she picked up Dean’s gun and handed it to Sam, and begged him for the only help the brothers knew they could give: to kill her before she would hurt or kill anyone else. What she asked of Sam was exactly what he had forced Dean to promise him in Playthings, what DemonMeg/Sam had tried to force Dean to do in Hunted: to kill whom he loved in order to prevent her from turning into something she wasn’t, something evil. This is the way you can save me. Please – I’m asking you to save me.
Watching Sam breaking, Dean tried to spare him – Sammy, I got this one. I’ll do it. – but Sam refused, because Madison had said that she wanted it to be Sam, and he felt that he had to do it. And so he did, despite his grief and the tears running down his cheeks – and we saw that scene play out, not between Sam and Madison, but on Dean’s face as he wept for Sam’s pain, and flinched in reaction to the shot, and died inside along with Sam, seeing himself in Sam’s place. And in my mind, I heard Dean’s voice in Hunted: He just said that I had to save you. That nothing else mattered. That if I couldn’t, I’d … I’d have to kill you. He said that I might have to kill you, Sammy.
I knew everything about this story before it ever aired, and I knew nothing at all. I knew nothing at all.And now I know all too much.