Here's a quirk concept I had:
The quirk requires the person to consume caffeine to activate, and depending on the amount of caffeine consumed, the faster the person's mind and body moves. Essentially, when they consume caffeine the world around them slows down, and the more caffeine they have determines how slow. It can reach the point where the person feels like they stopped time. However there is a drawback. Again depending on the amount of caffeine consumed, once the caffeine wears off the person will begin to feel lethargic and exhausted. If pushed to the limit the person might go into a short coma.
Anyway this idea popped into my head while working on Season 2 of my "Heros" story. Have a great day and I'll post soon.