The cavern is not actually under Middleton. It’s not really under an English forest, either. As far as he’s been able to tell, it exists between the everyday world and the Other Side, outside of time.

This is where Eric learned to use his powers, where he learned the craft of magic, from Merlin himself. He knows he wasn’t the first. There were others before him, from his world, and from others, too. Merlin trained them all.

Eric is not sure why Merlin was imprisoned here, in this weird space in-between reality and legend. There are many places where the history relayed by Merlin, the entity who lives here, matches up with Merlin, the character known in a hundred different books and movies. And many other places where it doesn’t.

There were always more pressing matters, anyway: demons and lost talismans and undying ones trying to breach Eric’s world. They never had much time for small talk.

All Eric really knows is that Merlin can’t leave the cavern. There is a small scrying pool by Merlin’s feet. It’s like a magical window to the outside world. Merlin can watch what’s going on, but he can’t interfere directly. All he can do is observe.

Now he scowls at Eric, just the way he used to.

“Took your time getting back here,” Merlin says, disappointed in his student, as always.

“This is the first time I’ve been able to use my powers in twenty years.”

“Oh, well,” Merlin says. “Twenty years. How terribly difficult for you.”

He’s still an asshole, Eric thinks. Some things never change.

Merlin shifts and glares at him again, as if he can hear Eric’s thoughts. (Which, you know, he could sometimes. Wizard.) He’d always complained that Eric was barely qualified to be a magician, despite his abilities. Eric wasn’t English, which was almost unforgivable, at least as far as Merlin was concerned.

But he taught and advised Eric anyway, because there weren’t any other candidates. And because the servant of The End was in Middleton, too. Eric was the only one who could fight him.

At least, that’s what Eric thought, until he found out about Alana, and Carrie, and Danny.

Merlin coughs and spits something black into a corner of the cave.

“You don’t look good,” Eric says.

“Quiet,” Merlin says. “They’ve almost broken my tethers to your world. Fouled the glade. You’ve been away too long, and you haven’t much time to set it right.”

“That’s why I’m here,” Eric says. “I thought it was over. We beat him. We won.”

Merlin gives him a bleak look. “Don’t lie to me, boy.”

“Colchester is dead. We killed him.”