I. Rubeus Hagrid doesn't fit in. He's not like the other kids with their neat robes and clever wand waving. He cries when they're introduced to Boggarts, but he runs after fearsome beasts in the Forbidden Forest. He has no friends, but writes to his Da almost every day. Classes never make sense to him, no matter how many times he tries to stay after class and get help. Yet Hogwarts is still his refuge.
II. Rubeus's role model is Newt Scamander, the famous Magizoologist. Every year, his Da gives him an updated copy of Fantastic Beasts and Where to Find Them for his birthday. Rubeus has all of them shoved messily under his mattress where the other Gryffindor boys wouldn't take them and rip them up. When he was nine, Da took him to Fantastic Beasts and Where to Find Them's 10th anniversary book signing. It was the happiest day of his life, and Rubeus keeps a picture of Mr Scamander and him inside his signed edition of the book.
III. The summer before his third year, his Da dies from a magical illness. Rubeus doesn't understand it much, but all he knows is that his Da—tiny, dear, sentimental Da—has been locked up in a box under the ground. Only Mr Professor Dumbledore can stop Rubeus from tearing up the ground at his grave. From that moment on, Mr Professor Dumbledore takes care of him. He refuses to go to an orphanage, so Mr Professor Dumbledore invites him to stay at Hogwarts until he is 17. He helps Professor Kettleburn with his creatures for the remainder of the summer, and only cries about his Da at night when he thinks Mr Professor Dumbledore will never know.
IV. At the beginning of his third year, Mr Professor Dumbledore tells him that he's invited Newt Scamander to come to school and give a presentation. Rubeus is so happy that he bursts into tears. Mr Scamander arrives on the third week of school with a large suitcase that seems lighter than it actually is, and tells Rubeus's Care of Magical Creatures all about the habits of an average Puffskein male, then signs everyone's copy of Fantastic Beasts. He draws Rubeus aside and tells him that Mr Professor Dumbledore has told him that Rubeus is very interested in magical creatures. He slips something into Rubeus's robe pocket, then awkwardly waves before walking away. When Rubeus checks the pocket later, he cries again, because it's an acromantula egg. Forget the 10th anniversary signing: today is the happiest day of his life.
V. It's the middle of the year when three things of great importance happen. First, the acromantula hatches, and Rubeus feels like a proud mummy and names it Aragog. Second, students have been attacked across the school. Rumour has it that some chamber has been opened by the heir of Slytherin, but all Rubeus is worried about is if Aragog gets Petrified (or worse, killed). After each class, he runs to the abandoned classroom where he keeps him. It's on one of these trips that a Slytherin prefect who wants Rubeus to call him Tom finds them. Rubeus tearfully makes Tom swear that he won't tell. The third thing is that Rubeus is expelled for raising Slytherin's Monster that killed a Ravenclaw girl. It's Tom's fault. Tom claims that Aragog is a dangerous creature, and no matter how desperately Rubeus tries to tell them that Aragog is harmless, they banish Aragog into the Forbidden Forest and snap Rubeus's wand.
hagrid! is! amazing! and! doesn't! get! enough! credit!