... the fact that she's naked, completely naked, in front of a guy, who's also naked.
She's never felt this vulnerable before, not even when confronting Amon and his Equalists. Again, Mako sense her insecurity and kisses her gently.
"It's alright," he whispers. "We can stop if you want. I won't hurt you, or do anything you're not comfortable with."
Gratefully, she returns the kiss.
"I don't want to stop," she confesses, blushing. Mako grins, kissing his way down her neck, leaving a small love bite on her collarbone. In retaliation, she grips him once again, eliciting a hiss from him, then strokes up and down a few times, marveling at the feel of him in her hand.
Korra's never even seen a guy fully naked – except on the diagrams they'd used to explain these kinds of things to her back at the South Pole. Fascinated, she watches his face to see how he reacts as she strokes him, marveling at how hard and hot he is.
She grins at him.
Suddenly, that smirk is back on his face, and then he slides one of his fingers into her. This time, it's her turn to emit some kind of unintelligible noise of pleasure at the feel of him inside her. Slowly, he withdraws his finger, adding another, pumping in and out.
She whimpers helplessly at how good it feels....