After the Straw Hats' battle at the Shabondy Archipelago, Sanji finds himself on an isolated island inhabited by ponies. There are a lot of problems to solve before he can find his captain and crew, but at least he has two extra legs to use now.
A continuation of Fullmetal Pony's Set Adrift story about Sanji. Disclaimer: This story's Sanji entered Equestria as a pegasus instead of a unicorn. It really doesn't change anything about FMP's chapter.
Check out the original story about Luffy for more background information that might only be implied in this one.
Rated Teen for the usual One Piece manga violence.
Edit: Wasn't easy to find a blue pegasus Sanji, but here we go. A placeholder until the purely hypothetical day that I commission a better picture.
I don't think the guy (or girl?) who drew this will ever be aware of my story, or my use of his picture, but I will nevertheless credit him and link to his Tumblr. Because it's the honorable thing to do and I don't want to be an ungrateful plotface.