Devil's Fruit

Yes, you all saw this coming. Devil's Fruit is an interesting part of the world of One Piece. Basically, the user is given a special, unique ability by eating an rare fruit, which often has swirls on it. There are three categories of Devil Fruits;

a) Paramecia

Paramecia-types are the most common type of Devil's Fruit users in One Piece; basically, it give the user special attributes and abilities, at the cost of it being, well, useless. An example is the Gomu Gomu (or Gum Gum) Fruit. However, these so-called "useless" abilities can be put to good use, for example, Luffy is an incredibly powerful fighter.

b) Zoan

Zoan-types have the ability to turn into a certain animal. They have three forms; their original, often human form, their full animal form, and a so-called "hybrid" form, which is a hybrid of their two forms. There are usually different "forms" of types of animals. For example, there's 3 types of Dog-based Devil Fruits; Jackal, Wolf and Dachshund.

c) Logia

Logia-types are the rarest of the rare Devil's Fruits. Basically, it gives the user the ability to become, use, and generate a natural element. However, we will not be allowing people to register with this type of fruit (unless they're a canon character). It may only be earned.

---

Basically, if you wish, you may register with a devil's fruit, however, you must have some sort of legitimate reason why the character ate a devil's fruit.