<P> Rowling has stated in an interview that Hagrid was in Gryffindor house during his time as a student . When he comes into possession of an acromantula, he is expelled from Hogwarts as his pet is believed to be the "monster of Slytherin". However, persuaded by Dumbledore (who at the time was Transfiguration teacher), Headmaster Armando Dippet agrees to train Hagrid as gamekeeper, allowing the boy to remain at Hogwarts . By the time Harry attends Hogwarts, Hagrid is also the Keeper of Keys and Grounds: the former, according to Rowling, means "that he will let you in and out of Hogwarts ." Part of his job includes leading the first years across the lake in boats, upon their initial arrival at Hogwarts . </P> <P> When discussing the killing off of characters in her books, Rowling said that she always knew she was "working towards the point where Hagrid carried Harry out alive--but supposedly dead--out of the forest". She said she had planned from very early on that Harry would walk to his death accompanied by the' ghosts', and that "he would emerge in Hagrid's arms". In her own words, "that's what always kept Hagrid safe". She said "Hagrid would have been a natural to kill in some ways", but that the mental image of this moment--a big fatherly Hagrid carrying the limp Harry in his arms--was so strong it decided his fate . She also liked the circular notion of Hagrid both bringing Harry into the world, and then bringing him back from the dead . </P> <P> Hagrid is introduced in the opening chapter of the first novel . Following the death of James and Lily Potter, Dumbledore entrusts Hagrid with rescuing the infant Harry from his parents' house after they have been murdered by Lord Voldemort . When Minerva McGonagall expresses her concern about the fact that it was Hagrid who would carry Harry to the Dursleys', Dumbledore says that he would trust Hagrid with his life, a fact that is demonstrated several times during the series, as Dumbledore frequently asks him to carry out secret tasks . Ten years later, he is tasked to bring the Philosopher's Stone from Gringotts to Hogwarts, and provides the three - headed dog Fluffy to guard it . Dumbledore also gives him the task of locating Harry, helping him to find his bearings in the wizarding world and to buy his school things . Hagrid is the first member of the Hogwarts staff to be introduced to Harry before he began attending the school . Hagrid later becomes friends with Ron and Hermione as well . Later in the book, a hooded person (Quirinus Quirrell in disguise) gives him a dragon egg to elicit details about Fluffy . Hagrid lets slip to Harry, Ron, and Hermione that the way to get past Fluffy is to play music, for which they use the flute Hagrid himself carved for Harry, which allows them to pursue the potential thief . The three also assist Hagrid after the dragon egg hatches, by helping to remove the baby dragon Norbert, who is taken to live in a dragon sanctuary in Romania where Ron's older brother, Charlie Weasley, works . </P> <P> Readers first discover why Hagrid was expelled from Hogwarts in the second novel . It is revealed that Hagrid was a student at Hogwarts at the same time as Tom Marvolo Riddle, the wizard who later became Lord Voldemort . Hagrid was expelled during his third year, after being caught in the company of Aragog, a dangerous acromantula: this already serious crime seemed worse than it was, due to the belief that the acromantula was "The Monster of Slytherin," and that Hagrid had released it from the Chamber of Secrets and allowed it to attack students . Aragog escapes into the dark forest and starts a colony of spiders . The belief of Hagrid's guilt was encouraged by Tom Riddle, the actual criminal, who had been using the true monster (a basilisk) to attack students, and who had framed Hagrid to prevent the school from being closed, because he didn't want to return to the orphanage . During the events of the second book, the Basilisk is unleashed once again and Hagrid is sent to the prison of Azkaban, as he is believed again to be responsible for the attacks . However, before being arrested, Hagrid tells Harry and Ron to "follow the spiders", so that they can meet Aragog and discover the identity of the true monster . After Harry defeats the Basilisk and uncovers the truth, Hagrid is freed from prison . </P>

Giant three-headed guard dog in harry potter and the philosophers stone