Beacon Hills, 2003

It had been two years since his wife's accident, and almost every lead had fallen flat. The miracle medic from Indonesia turned out to be a sham. The memory potion from the spiritualists in Zimbabwe killed more people than it saved. The only one left had been a farfetched myth about Horsemen and the Wild Hunt. They were supposed to be commanders of memory, but they were cursed upon their creation, a curse that, once broken, would free their powers.

But somehow Michael had found them, had reached their base of operations. It was a camber of tunnels that technically existed between dimensions. After an exhaustive trip around ancient Germanic sites, he had gotten all that he needed. Once inside the tunnels, he used the power of the Peitsche, their sacred whip, to command them like an army.

It was a lonely pursuit, since the Horsemen were less than people and couldn't talk, but he knew it would be worth it once he figured out how to break the curse. He spent every waking hour pouring through mythology and historical documents that could give him clues. When he wasn't doing that, he was examining every inch of the Horsemen's tunnels. He knew that there had to be a way to lift the curse, because the alternative was to believe that he had done all of it for nothing. That his wife would never remember or love him again.

Finally, one day, when he had almost reached his breaking point, Michael stumbled upon a hidden room within the tunnels. It looked like a shrine of some sort, and when he went up to the altar, he found a tablet inscribed with ancient text. He translated it from ancient Germanic dialect:

The Horsemen may only take away what lives in the mind. Until the key has untethered the mind and the heart, they will never reach their full power.

This insight led him to a story about the curse he had not noticed before, for it had never mentioned the Horsemen directly. But it spoke of killing the "key" in a ritual sacrifice in order to restore the rightful power of a clan of ghosts. He realized that the key would have to be someone who could not be forgotten, someone whose emotional tether was so strong that, by breaking it, he would unlink the mind and the soul.

So he travelled around with the Horsemen, looking for the key. Sometimes, people had to be taken, some got hurt, some got killed. Eventually, Michael stopped caring about killing people, stopped worrying about who he hurt. All he wanted was to find the key and restore his wife's memory. He wanted her to love him again, so much so that he stopped caring about whether or not he deserved it.

Underground Tunnels, 2016

"Well aren't you the smart one," the man says, eyeing Lydia with a smile on his face. "Tell me, sweetheart, do you know why I need him?" The man looks almost amused and Lydia wants to slap the expression off of his face.

"If he's the tether, that means he's holding something together. But if he's also a key, that means he can unlock that very thing," she says, beginning to understand it all but afraid of the answer she's come up with. The man nods his head enthusiastically.

"You're on the right track." The man paces but doesn't come towards the pack.

"We didn't forget him, even though the Horsemen tried to make us," she continues, putting more pieces into place. Lydia looks around the room, assessing the altar to her right, which seems to have an inscribed tablet on it. The text seems Germanic in origin, but she can't be sure. Still it seems familiar. And then, suddenly, it clicks into place. The Horsemen, the Temple-like room they're in, the tablet.

Lydia read a history of folklore book once, and in it there was a story about ghosts chained up by a curse that tethered the mind and the heart, keeping them from reaching unlimited power. It was meant to save them from themselves, but that wasn't good enough for one of them, and so he searched for a key that would break the tether. The key turned out to live inside the most beautiful maiden in all the land, and he ended up falling in love with her. They lived together happily for a while until she realized that he was a ghost. That night, brokenhearted and naive, she took her own life. This unlocked the ghosts powers, and most of them rejoiced. But they ended up destroying themselves, the new power too much for them to handle.

"It's a sacrifice," Lydia announces. "You're planning to kill Stiles so that the Horsemen can become all powerful." The man actually looks surprised for a second before beginning to slowly clap.

"Smarter than I thought," he admits. "Took me months to figure it out." He laughs and grins at Stiles. "I can see why you care for her so much." His expression almost turns wistful.

"Why do you want them to be so powerful?" she asks. " You're not even one of them."

"And I don't want to be. But I need them to do something for me, to restore something that was taken a long time ago."

"And what would that be?" Scott asks.

"My wife's memories, of course."