Sebastian was in his shop, dealing with expendables who came in to buy stuff. He couldn't care less what you were doing at the moment, as you were nothing but an annoying and aggressive pest in his eyes. Which isn't exactly wrong, as you often ambush him from the vents, though it's never too serious. He picked up on a habit of often looking up into the vents just to be sure you're not about to throw yourself at him and try bite his arm off or something. It has been quite annoying.

After the expendables left, he picked up his stuff and crawled out of his store to go scavenging. He knew you were most likely hiding in the vents, because you were mostly a vent dweller, but that still didn't make him feel any less paranoid. He needed to go through the vents to get more data and stuff for his shop, and he knew it was risky considering you claimed those vents as your territory, and the fact that he didn't know his way around in them the way you did. You made it seem too easy.