[He finds it terribly endearing when Vergil has to look away from him. Particularly when he does the same thing a moment later, and they're left catching glances in very small bursts or out of the corner of their eyes.

Honestly? He wouldn't have held it against Vergil if he did make an effort with Nero out of guilt, or duty, or obligation. Vergil could have stuck around because he wanted to borrow Red Queen and Nero would have agreed to it, at least initially. None of that really mattered when it all led to the same outcome: a father who existed in his life. A father who wanted him.

Hearing him say that...]

I can't explain it, you can't explain it... we're really sitting here grunting back and forth, huh?

[There's the other snort. And this time Nero is definitely crying, though it's in the form of a few tears spilling and his chest shaking, while he stays in control of his voice.]

You really are my dad.