[Okay, Percy's definitely noticing something off about Nico, don't think he isn't.
Thankfully, Nico manages to land a blow before anything life-altering happens to Percy's limbs and the dragon's left to deal with a new burst of pain. With zero hesitation, Percy dives forward toward the soft flesh again, Riptide at the ready, as he plunges the sword into where (gods help him, he doesn't know dragon anatomy) there'll hopefully be something vital.]