Spike At Your Service

S3, E9: When Applejack saves Spike from a timberwolf attack in the Everfree Forest, he insists on helping her around the farm in order to repay the life debt he feels he owes her. His efforts only make trouble for her and the other ponies, and they set up a fake timberwolf attack for Spike that he can save Applejack from, thus making him feel satisfied with his debt. Their ruse draws a pack of real timberwolves, which Applejack easily crushes, but the pieces form into a single giant beast and she gets caught in a rockslide. Spike causes the timberwolf to fall apart by throwing a rock down its throat, and frees Applejack. The two decide not to worry about repaying favours done for each other in the future.