Harry Potter and the Half-Blood Prince
Professor: Care of Magical Creatures
Affiliation: Order of the Phoenix
Hagrid has a difficult year at Hogwarts. First, his three favorite students and Hogwarts friends have dropped his class (Care of Magical Creatures). Second, Hagrid must contend with the death of Aragog, the giant spider who lives in the forest.
When Harry, Ron, and Hermione visit Hagrid for the first time during their sixth year in the hopes of making peace with him after they dropped Care of Magical Creatures, Hagrid is none too pleased: "Hagrid stood and looked at them all for a split second, then turned and strode into his cabin, slamming the door behind him" (11.84). Usually the warmest and most welcoming of hosts, Hagrid displays uncharacteristic coldness here, and as a result, we understand just how hurt he is.
Hagrid has a big heart, especially for magical creatures. No one knows them or cares for them like he does. At first, we are not that interested in the fact that Aragog has died, but Harry helps us understand just how devastating this blow is to Hagrid:
He had known Hagrid to present a vicious baby dragon with a teddy bear, seen him croon over giant scorpions with suckers and stingers, attempt to reason with his brutal giant of a half-brother, but this was perhaps the most incomprehensible of all his monster fancies: the gigantic talking spider, Aragog, who dwelled deep in the Forbidden Forest and which he and Ron had only narrowly escaped four years previously. (11.116)
Because of his ability to love deeply, Hagrid must grieve deeply. Despite the bumpy ride, Hagrid remains the awesome dude that he is, constantly protecting and helping Harry, Ron, and Hermione.