There were a myriad of things Remus had learned to use in combat over the years: his strength, his senses, odd spells. One other thing he'd learned out of necessity was that sometimes you had to use an opponent's weakness and nature against him. Nor would the enemy they faced play a fair and honourable game while trying to kill them all.
Still, this was Harry and he did feel a twinge of guilt as he lay unmoving, eyes closed, waiting...just waiting for Harry's good nature to bring him closer. The nice man everyone saw when they looked at Remus would never do such a thing.
But, it was the hardened werewolf who had been forced to learn how to fend for himself against all odds for nearly a decade that opened his eyes and curled his fingers around Harry's throat as he knelt at Remus' side. He used that grip to throw Harry over his own body as he rolled, grabbing Harry's wand hand as he did and using the other man's own wand to cast Petrificus at point blank range when they landed.