"Of course you are," Barry said with a roll of his eyes. It didn't surprise him at all that Snart would steal his marshmallows. "You know, I thought if you were going to resort to thievery right after you got here, it would be something more interesting than marshmallows." He paused a moment, remembering who he was talking to. "That's not a challenge, by the way." Not that he thought Snart needed a challenge to steal something. He was pretty sure it was just part of him at this point.
Part of Barry wanted to snap that he understood, better than probably anyone, that people died. That you couldn't save them. That his own mother had died in his arms because he couldn't save her. That Eddie and Ronnie had died heroes while he hadn't been able to do anything to stop the Reverse Flash or the singularity. But he was tired and it was easier to latch on to Snart's reminder of his verbal fumble earlier. At least that was a topic that didn't make him feel helpless.
"You keep telling me you don't have any good in you, but I don't buy it," he said dryly, before he realized he had a chance to throw Snart off his game and a slow smile spread across his face. "Still, if you want some, good in you that is, you only have to ask." It was a terrible line. The most cheesy pun he'd used, probably ever. It wasn't even like he was trying to pick up Snart. He just really wanted to get under his skin. To get the better of him just once.