This is Garrett. He's probably one of the nicest guys you'll ever meet...if you ever meet him! He's a shut in, but only because he chooses to be. 

Garrett doesn't like that his heart beat is connected to time. And when he gets excited, it skips him forward in time (and slows down time for when he's depressed). So far, he's only been able to affect his own timeline. 

Unfortunately, because of his condition, Garrett has suffered through and missed some important moments in his life. When his parents died, time almost came to a complete stop as Garrett was swallowed with depression. He also missed the birth of his niece. He so excited that he sped through the whole ordeal and has only fleeting memories of that day. 

Garrett also tried dating, but failed. He would become too nervous or too excited and miss the whole date. The women he dated got to know him very well but he never got the chance to get to know them. 

When Garrett changes time, he only changes his own. Everyone else lives through time regularly, but Garrett skips ahead or stays behind, either being caught up to or having to catch up.