No one really bought into the idea that Groot was actually in any danger when he wrapped the Guardians in a snug ball to protect his friends as the Dark Aster plummeted towards Xandar, but boy does he have a way with words. Its a testament to the brilliance of Marvel that an exchange between an irascible raccoon and a talking tree can elicit genuine emotion. You can pretend you werent at least a little moved by Rockets obvious torment when his companion/muscle/houseplant showed he was prepared to make the ultimate sacrifice, but no one will believe you.