Her breath caught when he set his hand over hers - but the challenge broke that moment and set her to laughing. He tore off the roof, and she easily took chase.
Eric was faster. She could tell already that he would quickly outstrip her in this way. So she scanned the path he was likely to take, and made her own shortcuts. A turn to the left instead of the right, a twist up around another chimney to catch the edge of a higher roof, pivot, leap --
-- she landed in a crouch a few paces ahead of him, twisted her head around and grinned, then took off again. He would catch her; he had to, with that speed. But still, she ran.