Stiles didn't really want to sit down. Honestly, he didn't want to be in the room with Natasha right now. He wanted to go back and be by Lydia's side. He did take a seat, eyes on Nat the whole time.
He knew he would be asked those type of questions. It was standard. "We were at the beach, we just got back to the car when someone came out of nowhere...it all happened so fast..." His story might be a lie, but it was a believable lie. He had gotten pretty damn good at lying to the cops in Beacon Hills. This was no different.