Paul could stem the brush of color in his own face, if he wanted to, but it strikes him as unfair, so he refrains. He has pictures of his other self (recorded by her, for posterity), and he knows his own looks. Really, he should take it as an objective assessment.

But it's not quite meant that way, although he doesn't think it's meant another. It has the same quality as Midoriya's comments about his form during sparring, which opens up an avenue of thought Paul steers himself away from immediately. Midoriya's heart is in his own open palm more often than not, and there's nothing to be read into that.

"He's right," Paul joins Midoriya in explaining, anchoring Kaworu down with the hand on his chest, sensitive to the minute twitch that often signals Kaworu's withdrawals, "He's also right about honor. But I wouldn't let anyone fight over you like that. It's presumptuous."

Naturally, it's not presumptuous of Paul to decide that certain duels involving his friends are off-limits.