It takes him a second to process that, and even when he does he can hardly believe it. But even after all these years, he can't forget Karkat's voice. He's always known about the raids and Karkat's role in them-- Hypatia wouldn't pass up an opportunity to remind him how often his kid almost got murdered by robots-- but having been stuck on the station for so long, he'd pretty much given up on the kid ever finding him. Why would he, anyway? Jack could have just as easily been dead right about now. There were more useful people out there the kid could be busting out.

Then he's hit with the realization that oh god Karkat is ass-deep in robot country.

"Oh, fuck-- fuck, kid, what are you doing here?!" he hisses, squirming and trying to figure out where the troll is standing so he can yell at him properly. So much for keeping Jack calm.