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Chopper is the Doctor of the group, extremely knowledgeable in the practice of medicine. Born a reindeer, he has the ability to transform into a human-like state. He gained this power by eating the Devils Fruit known as 'Hito Hito no Mi' (Human Human fruit).

Chopper, during his life as a regular deer was constantly rejected by his herd because of his irregular blue nose. Upon his eating of the Devils Fruit, he was forced out of the herd altogether. In turn, he decided to seek acceptance from the humans and traveled into town. The villagers however, thought him to be a monster and attacked him. In terror he fled into the woods where he met Dr. Hiruluk, who became his friend and mentor (even though he wasn't really a doctor) and even gave him his name, stating that his horns looked as though they could chop down trees. Hiruluk's dream, as he told Chopper, was to cure his country. However, because of his lack of medical skill, he tended to just make things worse. During this time of bonding with Chopper and failing at medicine, Hiruluk is dying of an incurable disease. When Chopper learns of this, he seeks out a mushroom which he believes is a magical cure, but is in truth poison. Though knowing it is poison, Hiruluk eats the mushroom, knowing that Chopper risked his life for it. Before the mushroom can take effect however, Dr. Hiruluk is tricked into going to the castle of the island's king, believing that the king's doctors are sick. However, it was a ploy by the king to lure Hiruluk there to kill him. Before this can happen, Hiruluk mixes an explosive drink and blows himself up. Chopper is left distraught and alone, he then seeks to truly learn medicine by becoming the apprentice of the 'Doctorine', another doctor on the island.

When the Straw Hats meet him, Chopper is terrified of them. His fear of being called a monster and attacked haunts him. However, with the defeat of Wapol (the tyrant king) Luffy persuades him to join as the ship's doctor.
As a member of the crew, he becomes quick friends with the others, his best friends being Usopp and Luffy. His timidness remains, and it becomes apparant that he is extremely gullible, often falling for Usopp's tricks and stories. However he is determined and will fight for his beliefs and people in need.

KNOWN RELATIVES
Reindeer Herd
Dr. Hiruluk (father figure)

FAVORITE FOOD(s)
Cotton candy, chocolate, anything sweet

ABILITIES
Chopper's Devils Fruit, being a Zoan type, allows him to switch between 3 forms at will.

Walking Point - This is his true form, which is that of an average deer. Although it is his true form though, he rarely will use it.
Brain Point - This form is his 'mid form', the form he most commonly uses. With this form he is able to be most strategic, and with the consumption of a Rumble Ball, he is able to 'scope out' an enemy's weakness.
Heavy Point - This form is his 'human' form. Though he loses his antlers, he retains his blue nose and fur. This form is a towering one, when in this form he is 3rd the third tallest in the group, exceeded in height only by Brook and Franky. He will most commonly use this form when in battle or when in public.

Along with the normal forms that come with his Devil's fruit (human form, mid form, and deer form), Chopper has a special medicine he made which he uses to increase his abilities. This special creation is known as the 'Rumble Ball' which gives him the power to have 4 extra abilities.

Jumping Point - This form allows him to keep his reindeer legs while in a human like form. This allows him to jump incredible distances at whim.
Arm Point - This form allows causes his fore-hooves to become extremely muscular, creating a powerful 'punching' attack which leaves a hoof print on the opponent.
Guard Point - This form causes Chopper's fur to grow long, encasing him in a large ball of hair. This causes damage done to him to be largely minimized.
Horn Point - In this form his human arms are retained and also become bulkier. His horns are also affected, growing to a huge size and becoming long and sharp.


Along with these 4 extra forms, is a more dangerous and deadly form. When Chopper eats 3 Rumble Balls within a 6 hour time period he loses control and becomes a gigantic and terrifying beast. This form is known as 'Monster Point'. In this form, Chopper loses all conscious thought and goes on a wild rampage, attacking both friend and foe.
As observed by Zoro, along with being deadly towards those in his path, the strain of the monsterous form also takes a toll on Chopper's body because of the massive energy used to sustain the form. The only way to stop the rampage is to force him into water.
This form is only used in desperation.