He kept pacing, fingers at work until he found his marker again. Then it was back to scribbling on the wall, his hands making those old familiar Gallifreyan circles, complex arithmetic in beautiful patterns. But then he blinked, and it changed. That would never work. The permutations were utterly wrong, the science he'd thought could back it up warped in his mind. With a snarl, he scribbled harder, angry black marks cutting through the formulae.
The marker snapped in his hand, leaking ink, and he slapped at the wall instead, leaving black hand prints. He dropped then, letting himself fall back and running his hands over his face.
A shrill bit of a laugh escaped him. "So this is what going mad feels like," he muttered. And then sighed. Pulled himself back up to his feet and resumed pacing. His thoughts were going faster than ever, and he couldn't keep up.