He's not sure that this should be taking his breath away the way it seems to be taking Ned's breath away, because he's the one doing it, not the one having it done to him, but no matter whether it makes sense or not, he's having a hard time catching his breath, so intent on listening to those noises Ned's making and seeing the way he's gripping the sheets like that. "You're so..." he manages, but hell if he actually knows what he's trying to say -- it's complimentary, he knows that, but what the actual words are he has no clue -- so he just breaks off into reverent silence, focusing entirely on Ned instead.

Ned's instruction is eagerly received, and he does as Ned asks, adding a second finger, still moving very slowly, but the excitement obvious on his face, on the way he immediately starts attempting to replicate the motions he'd been doing before, with just the one finger. If that had been good, and Ned says this will be even better, he can only imagine what kind of reaction Ned will have to it, but he knows he's desperate to see it.