Devil Fruits are distinctive fruits that are scattered throughout the world of One Piece. They grant their users superhuman powers and in exchange take away their ability to swim. The origin of the Devil Fruit is unknown.
There are hundreds of Devil Fruits with various powers that can cause mass destruction. They are quite rare and only one of each kind is present. This is the reason why people are trying to mass-produce artificial versions of Devil Fruits for war purposes. A person can only have one Devil Fruit at a time, as they would die if they consume more than one.
It is unknown where these Devil Fruits come from and how they work. These fruits come in all different shapes and colors and also have swirls or different patterns. The only exceptions are the artificial Devil Fruits which have rings on them. They have existed for almost 800 years. When the user eats the Devil Fruit, it gives them a special power and they come to be known as a Devil Fruit User. There are more than 100 Devil Fruits, but only one of each Devil Fruit exists. They also taste very bad and strip away the user's ability to swim.
The consumer only needs to take one bite of the Devil Fruit and after that, the Devil Fruit becomes a simple, useless and disgusting fruit. Despite this fact, many people have eaten the whole fruit. The consumer doesn't need to wait for the fruit to digest as the whole consumption process is quite fast. A person can only eat a single Devil Fruit in their entire life and if they try eating a second one, then their body will be torn apart and they will be killed.
There is a method to steal the Devil Fruits from a dead body of a previous Devil Fruit user, but the way to do this is still unknown. Even though eating a Devil Fruit affects the consumer's genetic blueprint, it doesn't cause any problems in their offspring. The World Government is always trying to get its hands on the Devil Fruits due to the immense power that they possess and some Devil Fruit users are also sold as slaves in the market. Each Devil Fruit has its own price depending on the powers that they possess.
There are various types of Devil Fruits:
This is the most common type of Devil Fruit. A Paramecia Type Devil Fruit grants its users superhuman powers. These powers include generating shock waves. It can also alter the features of the user's body and grant them abilities like a slippery physique, the ability to split their body from their own body, a body made of blades, etc. It also allows some users to modify people, objects, and their surroundings by levitating things or turning people into toys. It also allows users to generate and manipulate substances.
Some examples of Paramecia Type Devil Fruits are Gomu Gomu no Mi, Bara Bara no Mi, Hana Hana no Mi, Ope Ope no Mi, Uta Uta no Mi, Doru Doru no Mi etc.
The Zoan Type Devil Fruits give the user the ability to turn into an animal as well as transform into that animal's hybrid form. Zoan-type Devil Fruit users have a will of their own. These Devil Fruits can even be integrated into objects, bring those objects to life, and grant Zoan-type powers. There are three sub-classifications of the Zoan type Devil Fruit:
This Zoan fruit allows the user to transform into extinct species like dinosaurs and they are quite rare. They're known to be very strong.
This Zoan fruit allows the user to transform into mythological creatures like dragons or phoenixes. These fruit users have special powers and are also quite rare.
These are artificially created Zoan fruits, aka SMILE. SMILE users are given enhanced physical abilities and can hold down powerful opponents. They also gain the abilities of the animal of the SMILE Fruit that they have consumed. They possess abilities of high resilience. Due to the illegal chemicals used for making them, only one out of every ten SMILE fruits will have all the abilities of a Zoan-type Devil Fruit. 90% who only intake one will not receive the power but will lose their ability to swim.
Some examples of Zoan type Devil Fruits are the Hito Hito no Mi: Model Nika, Cesar's SMILE, Hito Hito no Mi, Uo Uo no Mi: Model Seiryu etc.
The Logia fruits are the rarest and the most powerful type of Devil Fruits out of the three. They allow their users to create, control and transform their bodies into any natural element like smoke, sand, fire, magma, ice, etc. They can also allow the user to transform into artificial elements like paper or syrup. The ability to transform makes the user tangible as well as allows the user to remain in control of their body when it's broken into pieces. They also gain every ability related to that element.
Some examples of Logia Type Devil Fruits are the Moku moku no Mi, Suna Suna no Mi, Mera Mera no Mi, Yami Yami no Mi etc.
As each Devil Fruit possesses a unique ability, they each require different countermeasures. These users are quite tricky to fight and deal with. As not a lot is known about the Devil Fruits and their powers, people who possess this power use it to their advantage. They utilize this misconception on how the power was achieved to manipulate their enemies for their own purposes. These powers are also quite hidden and sailors spend their lives finding this power. There are Devil Fruits which have high offensive power and are known to cause damage on a large scale. But at the end of the day, the strength of the Devil Fruit depends on the users.
The most known weakness of a Devil Fruit user is their inability to swim. Even though people know this, the accurate version is the weakness against seawater. The ocean is quite deadly for all Devil Fruit users. Oda mentions that moving water like waves or rain doesn't affect the users but still water like lakes or rivers does affect them. These users have to be really careful as they are always at a high risk of drowning and their enemies can also take advantage of this fact and defeat them. This is a high risk to those who can't breathe underwater as on the other hand, Fishman who consume Devil Fruits are able to breathe underwater and aren't subject to this risk. However, even if a Devil Fruit user could breathe underwater, they are still unable to move. This immobility makes the users vulnerable to dangerous underwater creatures. Even if half of their body is submerged, the users cannot use their Devil Fruit power. The user will only be affected by water if they're physically touching the water.
A. Blackbeard and his crew are the only people who know how to do this.
A. According to Marco, Blackbeard has a unique body structure and thus he can possess two Devil Fruits, while any other person can die if they possess more than one Devil Fruit.