Dobby the house-elf to the Malfoy family debuts in the second Harry Potter movie. Harry finds him in his bedroom the evening Vernon Dursley and his wife, Petunia host the Masons in the hopes of securing a business deal. They instruct Harry to stay quietly in his bedroom, pretending that he doesn't exist. Clearly, at no liberty to come downstairs, much less entertain a house-elf, Harry finds an impish creature with enormous green eyes jumping up and down his bed. The creature stops and introduces himself as "Dobby the house-elf" and says it's an honor to be in presence of Harry Potter.
Dobby lives a miserable life being that he is the resident house-elf of Malfoy Manor, and in servitude to the Death Eater, Lucius Malfoy, and his wife Narcissa. He is neither used to wizards being polite to him nor being asked to sit down like an equal before having a conversation. He says he heard of Harry's greatness and admits he hasn't met many "decent wizards," implying mistreatment at the hands of the Malfoy family. He's dressed in what looks like a grubby pillowcase with arm and leg holes. Harry's kindness makes him burst into noisy tears, and he punishes himself by hitting his head against a chest drawer for almost speaking ill of his wizard family. Dobby doesn't make a first great impression at the beginning of the second Harry Potter installment, but it's clear that he's risked everything to warn the young wizard that it's dangerous to return to Hogwarts School.
Dobby Is Bound To Serve The Malfoys
In Harry Potter and the Chamber of Secrets, Dobby tells Harry that he's bound to serve one family forever, unbeknownst to the young wizard that he's eternally bound to serve the Malfoys. Dobby comes to see Harry Potter because he wants to protect him. He warns him to stay away from Hogwarts because there is an impending "...plot to make most terrible things happen." Dobby says he's known about it for months and doesn't want Harry in peril. It turns out, he even intercepted Harry's letters in an attempt to discourage the young wizard from returning to Hogwarts. Dobby, in his mind, thinks if Harry believes his friends have forgotten about him, he wouldn't want to go back to school.
Unable to convince Harry to stay away from Hogwarts, Dobby sprints down the stairs, levitates Petunia's pudding with a Hover Charm, and dumps it on Mrs. Mason's head. Harry is made their prisoner in his room, and Uncle Vernon fits a bar on his window, vehemently declaring he will never let his nephew return to Hogwarts and see his "freaky friends." Harry is eventually rescued by the Weasleys, Fred, George, and Ron (Rupert Grint) in their father's Flying Ford Anglia. Up until that point, Dobby comes across as a destructive nuisance and is yet to become the fan-favorite and revered character that he's now deemed to be. He visits Harry once again in The Chamber of Secrets after the young wizard ends up getting his right arm broken during a Quidditch match.
"Harry Potter should have listened to Dobby. Harry Potter should have gone back home when he missed the train," says Dobby, leaving no room for doubt that it was he who stopped the barrier at Platform 9 3/4 from letting Harry and Ron through. He tells Harry he remembers how it was for house-elves before the young wizard triumphed over Lord Voldemort, in that, they were treated like "vermin" earlier. While maintaining he's still abused, Dobby reveals that the old pillowcase he wears for clothes is a mark of his enslavement and that he can only be freed if his master presents him with clothes. With that, Dobby warns Harry once again, snaps his fingers, and disappears from the Hospital Wing. He reappears at the end of Harry Potter and the Chamber of Secrets with his insufferable master, Lucius Malfoy.
Dobby Is A Free-Elf
All this while, all Dobby has wanted was to warn Harry about Lucius Malfoy's involvement in the opening of the Chamber of Secrets. He wanted Harry to be safe and thus tried his best to dissuade him from going back to school. It turns out, Lucius had snuck Tom Riddle's Diary into Ginny Weasley's cauldron of school supplies at Diagon Alley. It is pertinent to mention that Tom Riddle was You-Know-Who's original name, and he'd abandoned it to assume the alias, Lord Voldemort. Sometime before his downfall, Voldemort had entrusted the diary to Death Eater, Lucius Malfoy. While the Malfoy was unaware that the diary was Horcrux (containing part of Voldemort's soul), he knew it could be used to re-open the Chamber of Secrets - home to the Basilisk that was allegedly supposed to purge the school of all Muggle-borns.
The bewitched diary forced and manipulated Ginny into re-opening the Chamber of Secrets, but Harry saved the day by defeating the Basilisk. He destroyed Tom Riddle's diary with the Basilisk's fang and eventually learned that the family Dobby serves is the Malfoys. The latter fact comes to the surface at the end of the second Harry Potter installment, during his altercation with Lucius at Dumbledore's office. The vicious Malfoy expresses contempt over Dumbledore's return to Hogwarts and is indirectly told off. He turns around and kicks Dobby down the stairs, prompting Harry to free Dobby.
Harry tricks Lucius into freeing Dobby at the very end of the second Harry Potter installment. He places his sock in Tom Riddle's Diary and gives it to Lucius who immediately tosses it in Dobby's direction. Harry then whispers to Dobby to open the diary, thereby freeing him of servitude. While Lucius is livid that Harry lost him his servant and attempts to harm him, Dobby stands in the way and protects the young wizard. His last appearance is in Harry Potter and the Deathly Hallows - Part 1, wherein he rescues Harry Potter and his friends from the Malfoy Manor. Just as the group is disapparating, Bellatrix throws her knife in their direction which fatally wounds Dobby in the chest. He dies in Harry’s arms at Shell Cottage and his last words are, "Dobby is happy to be with his friend, Harry Potter."Dobby's death is a tragic moment in the Harry Potter series, and it leaves Harry inconsolable. Luna Lovegood closes his eyes and the Trio gives him a proper burial.