Every person can only eat one fruit, otherwise they explode. The sole exception is Blackbeard. It's still unclear as how he succeeded in obtaining two Devil Fruits, however it's pretty certain that he's the only one who was capable of that and it's nearly certain too that he isn't going to go for more than two DF.
I want to know more about devil fruits.
On what kind of plants do they grow, where do they grow, If a devil fruit user dies will the devil fruit grow again. Some fruits are well known like Thatch's Yami Yami no mi. And fruits like Kalifa's and Kaku's are unknown for their abilities.
And I hope that the strawhats find a devil fruit sometime along their journey. Pretty interesting discussion if someone should eat it or if they should sell it or something.
There can only be one fruit of each ability at a time. There is only one Rubberman, Lightman, Sandman etc. at a given time. However when the user dies, the fruit will be reborn. You can easily deduct that from the fact that there exists a book of DF. How is it possible that if only one fruit exists (that fact is confirmed) it appears in a book? That's not possible unless it had been seen in the past and its powers confirmed.
But because there are so many DF, a lot of them are still unknown.
Agreed with the person above me.
And, i would like to know if Luffy can eat one more DF and i also want to know more about Haki!
Well to be honest I have been trying to figure out how Blackbeard is able to be able to have two different Devil Fruit powers outside of people presuming that it's due to his body structure. Which may be the case but also I wonder.....outside of an abnormal body structure, if someone is capable of mixing two different Devil Fruits such as mixing the Paramecia Devil Fruit with a Logia Devil Fruit. Such as Blackbeard.....his Yami Yami no Mi (Dark-Dark Fruit) being a Logia and then acquiring Whitebeard's Gura Gura no Mi (Tremor-Tremor Fruit) being a Paramecia.
Now if that would be the case then I have a strong feeling that SOMEHOW Luffy might "acquire" his brother, Ace's Devil Fruit power of the Mera Mera no Mi (Flame-Flame Fruit).
Now I know that is a big if but it might happen just to be able to fight against Blackbeard
Nah that's just BS. If it was something simple as just two different categories of fruits there should have been multiple people in the past who had two DF. And no Luffy will never obtain the Mera Mera no Mi nor any other DF.
I don't want to see Mera Mera Luffy, sorry Zanji.
I think the fruits come from one tree (All of them), which grows on Raftel. A legendary tree like Treasure Tree Adam and Sunlight Tree Eve. When the fruits mature, they fall from the branches to the sea, and the they travel to all corners of the world. I assume that, when Ace died, the tree started to grow another Mera Mera no Mi(Flame Flame Fruie).
Now, about Blackbeard, I don't know if he has an abnormal type of body because he ate the Yami Yami no Mi (Dark Dark Fruit), or despite having eaten the Yami Yami no mi. I think it is part of the fruit's abilities, but I can't be certain.
Well it has been stated early in the manga that DF originate from the Grand Line and it's highely likely a place where no or rarely men come considering they can be sold for a 100M. Even though the idea of having a tree dropping its fruit into the ocean is plausible, it's quite odd that when you eat it you become a hammer, but the fruit itself can float xd
And about BB there can only be two explanations:
1) His body is something special, even without his DF, that allowed him to eat two DF. In the anime they translated it as his body structure is special, but in the manga it was translated as him bying atypical.
2) It's an ability from the Yami Yami no Mi fruit and personally I go for this one. The Yami fruit is "darkness" or with other words its "emptiness" or "void". Normally your body transforms into the element of your logia fruit, but his element is void, it's non-existent or with other words atypical. How can you transform your body into something that does not exist? So his body remained, however it became "empty" and that emptiness was filled with the Gura Gura no Mi. You could say that he was given a free slot.
The reason as why I think it's this is because BB was obsessed with the Yami fruit but why? Sucking things up and throwing it out is a powerful ability, but not really that special to say you place it above all else. The ability to nullify a DF power maybe, however that's something Haki can do too and he needs to make contact. It has also been shown it's still a very flawed ability. But what if he realized he could use it to obtain another DF power? That would make a lot of sense: a logia fruit that enables you to eat yet another fruit.
I also think that BB sucked out WB Gura Gura no Mi the same way he nullifies DF powers: by touching them. He just grabbed WB or something and then started to suck the DF power into himself. This is also why I believe he can't absorb any other DF anymore as this void is filled and even if that isn't the case I'm pretty sure Oda isn't going to give him anymore DF powers.