The Flash, Season 4

Barry:
I've faced a lot of bad guys. People who would hurt the ones that I love, destroy everything good in the world and think nothing of it. But this guy, he feels more dangerous than all the others combined. And we still know barely anything about him. Scares the hell out of me, Iris.

Iris:
Barry, how many times have we been up against the unknown?

Barry:
This is different.

Iris:
How?

Barry:
Ever since I came back from the Speed Force, I have been... constantly and genuinely happy. My friends are safe. Joe's gonna be a dad, again. And next week, I get to marry the love of my life. I have more to lose now than ever before.

Iris:
Yeah, but, what about after Cecile has the baby? Or after we get married? Or even when we have our first child? You know, as time goes by, there's gonna be even more for us to lose. And people are always gonna be coming after us. You can't let that consume you. You just have to live in the moment and face it as it comes.

Barry:
How are you not scared?

Iris:
Because we're the Flash. [Iris and Barry kiss]