Rivaal continued his reimancy fueled run for as long as he felt was safe, and then slowly dissipated the energy as he slowed down. For the excited Arev though, he paced himself, and then worked back to a full sprint.
They were only half way through the route he had started to work out, and he dodged a stray passerby. After screwing up his step though, he started to trip, but catching the fence of someone's home, he managed to balance himself and stop. At that point, he realized that he'd used a more energy than he'd expected. He wasn't that far above a beginner with flux magic, and so he paused to rest and let Arev catch up.