"Oi!" With a short bark of a laugh, Sirius took off after Gaius. They raced through the woods, leaving a narrow trail of destruction through the bluebells. Gaius was fast and agile, but Sirius didn't want to change form. That would be almost like admitting defeat. He might, considering his line of work, be able to keep up this pace longer.
And then there was the excitement of the chase, with its very tempting prize, all the better if he could catch him in human form.