SUMMARY

Shanks and the Red Hair Pirates have never possessed Devil Fruits, and it is to protect Joy Boy.
The previous Joy Boy might have drowned due to his inability to withstand sea-water.
So Shanks has the responsibility of saving Joy Boy if the same circumstance happens again.

Shanks, one of the strongest pirate captains with an impressive crew, has never consumed a Devil Fruit. In fact, none of the Red Hair pirates have any devil fruit powers in One Piece.

Yet, they are a crew feared across the world. But how is it that an entire crew does not have a single devil fruit user? Is it because Shanks chooses them based on these criteria? A One Piece theory attempts to explain why it is important for the Red Hair pirates not to consume any devil fruits.

Joy Boy was Defeated Because of the Devil Fruit Side Effect

Gear 5 Luffy in One Piece | Toei

Spoiler Alert!
One Piece manga and anime spoilers ahead

Joy Boy was an extremely strong individual who was eventually defeated, but no one knows how. However, according to the recent announcements by Vegapunk in the manga, the world was flooded with water as a result of the battle.

According to a theory, the final blow to Joy Boy actually came from his own devil fruit. As you must know, Devil Fruit users have one fatal flaw and it is weakness towards seawater, which causes them to lose their ability to swim.

It seems like this disadvantage was set up to come into play at a very crucial stage. What if it was this inability that led Joy Boy to eventually lose his life? In fact, the flood might have been induced purely to take out the rebel.

Joy Boy could have lost during the Void Century not because he was weak but because being a devil fruit user doomed him. After the first Joy Boy drowned, his comrades realized which fatal mistake to avoid when Joy Boy reincarnated next.

Shanks and His Crew Need to Protect the Next Joy Boy in One Piece

Shanks has never been defeated in One Piece | Toei
Once Joy Boy was defeated due to his inability to withstand seawater, his Devil Fruit user comrades must have also equally suffered if not drowned. In the end, no one was able to revive Joy Boy. After this incident, the well-wishers of Joy Boy have orchestrated a plan to protect the next iteration at all costs.

Shanks is likely to have been appointed to aid Luffy, the present Joy Boy in his quest. Shanks received the straw hat of Joy Boy which he had passed onto Luffy. Why did Shanks become a Yonko if he really wanted to protect Luffy?

The answer lies in how Luffy found the Hito Hito no Mi fruit. The Gorosei have been searching for the fruits but never found it in decades, yet Shanks had found the elusive fruit. Shanks might have already been on his mission and being a Yonko was just to keep an eye on the whereabouts of the World Government.

Given that Shanks shows up whenever Luffy is in trouble, it is highly likely that he is keeping an eye on the new Joy Boy at all times.
Shanks and Luffy | Toei Animation
Now, let’s talk about why the Red Hair Pirates haven’t consumed a single Devil Fruit. It’s very simple: this is to assure that if Joy Boy is once again affected by water, he has a whole crew of unbeatable non-Devil Fruit users who would protect him.

Since Shanks was in the pirate king’s crew, he might have been passed some top secret information after which he departed and created his own crew. Being a Yonko not only gives his crew immunity but also helps him examine the moves of the Gorosei. In fact, he could betray the World Government at any given moment once Joy Boy needs him.