In The Flash Season 2 Zoom is the villain to take on Barry and he is actually Hunter Zolomon but acts as a friend named Jay Garrick. He had a similar tragic back-story like Barry with his mom dying and he thinks he and Barry are the same.
Zoom: We're not so different, you know. What happened to us when we were kids. You could have just as easily become me.
Barry: No. I'd never become like you.
Zoom: 'Cause here's the thing. I know you. I know you, I know what's holding you back. You and me... we're really just the same person.
Barry: [scoffs] Yeah, you keep saying that, but it's not gonna make it true.
Zoom: You'll see. We are. Same tragic background. Same reason for running. Same desire to be the fastest, to be the best. The difference? You think your anger is dirty somehow. You want to be seen as pure, the hero. Doesn't it get exhausting? Doesn't it get exhausting, Barry! It was exhausting playing Jay, believe me.
Barry: I'm not pretending.
Why does Zoom keep thinking he and Barry are same ?