One Piece: Forced to Eat the Zombie Fruit in Impel Down

One Piece: The Really Overpowered Kind

Awesome.

One Piece: Protagonist Eats Devil Fruits Without a System

A novel where the protagonist has no System throughout the story and grows in strength by eating fruit. Is the plot good? The protagonist isn't goofy, right? It's action-packed all the way through.

Any One Piece Fanfiction Where the Main Character Is Sealed Away for Being Too Powerful?

Sealed away because he was too powerful.

Any One Piece Stories? No Saintly Protagonists, and the Longer the Better

One Piece.

Has One Piece Gone Downhill? Looking for Recommendations