If there was one thing Oliver had learned from his travels with the Doctor, it was how to run effectively--and stop when necessary. Such as at the edge of a cliff. In this case, he stopped himself amidst the tile, slightly wobbly but still standing.

He was unable to keep from laughing at Sebastian's rather-impressive slide followed by a less-than-impressive stop. "Hey, you okay?" he called, his concern genuine even if he was still smiling in amusement at his friend.