He sees him first, watches him for a moment, then runs and grabs him by the back of the neck. It's not the most charming hold - Derek is stronger than Jackson because he's an alpha, and it's the kind of hold that makes people think of a mother wolf carrying a cub.

But then maybe Derek does think of Jackson as a cub.

"Where are you going?"

There's enough of a threat in his growl that it's clear he doesn't want a bullshit answer.