At first, Aaron didn't know what to do as Piper's shock seemed to wear out into something like the panic from before. He understood, however, that they were moving toward safety rather than truly fleeing something behind, and so he pursued, with some vague notion that this guy was his responsibility until he got to wherever he was going. There was a brief hesitation at the foot of the dark stair, but it climbed, and then the cold winter air hit him hard, and he realized that the spooky garden was actually on the roof.
Aaron had an advantage over most, however, and he knew there was no one and nothing that wanted to hurt him in the darkness. He pursued Piper to the glass doors hidden by the curtains, alarmed by his behavior as the panic continued to spiral. "Stop!" When Piper did not respond, Aaron hesitated and then, pulling his sleeve over his hand, he pulled on the neck of Piper's shirt, avoiding Shane's coat as best he could.
The thin protection was not quite enough, and Aaron's eyes briefly glazed over as every recent, strong emotion took over.