Christ, the universe where they'd all collided. She wasn't aware of the Crisis as far as he knew. She might not even remember that he was the reason Zatara had stuck around and let himself be destroyed--because he wasn't about to leave Zatanna alone with Constantine, a worry that wasn't entirely unfounded.
John Zatara's death was one of the heavier weights of guilt Constantine carried now.
He didn't falter with the flirtatious smile though, it wasn't his way to show the guilt on the outside. Instead, he took her hand, glancing at the scar there. For his part, the rune he shared with her and Nick was itching like hell. He held onto her hand like he was afraid she might disappear, having greatly underestimated how much touching her again would make him feel, even a touch as innocent as this one.
"Gods," he whispered, staring at her. His expression betrayed him finally, a seriousness to it now. "I missed you." His way of saying, yes, he was aware of which world she came from now, and he was aware of how distant they were there--very on and off again.