
luffy is like a stronghold to them he makes them happy and keep them going if u can find something like that u don't want to let go
everyone have something in their lives that they want to run from if u look back they all try to run from it but he saw and felt their pain and really look at them like a real nakama and it really means a lot if u watch the anime of read the manga u see their emotions and feel it
esp when they were separated how each one felt while been attack in the forest (11 supernova) they were all hurt badly but they did not want to be separated from him
I love anime and manga whenever I am down I listen to my anime songs and I pick right up I wish people like luffy were real

I have always seen those kind of plot in every kind of movies and manga mate, but one piece has the best one so far... (no romance lel) usually there would be romance in it but this manga concentrates on adventure. For example: Disney Princess , mostly has no father/mother XD but really idgf cuz that's oda's way on making a story , little by little he will make more surprises and more unique adventures. Teaches you about friendship and all.... I just wanna hug oda tightly for being an author of this manga lel! ×D
Sorry if this is sound so rude but it's just my opinion and theory.
Well, after follow this story from about more than 10 years I found some pattern that always happen in this story except for the main purpose to find One Piece, it's about the strawhat crew who leave them and how Luffy tries to get them back. first is Nami, follow by Ussop and then Robin. And now the issue about Sanji so now we will see the story about Luffy and his nakama trying to get Sanji back (ONLY MY OPINION).
And all strawhat crew almost have same past about their childhood story. (lost their love one/family and want to be strong and achieve their dream so the one leave them will feel proud about it).
1. Luffy : he lost one of his dear brother (Sabo which is we know alive) and motivated to become strong and then he lost Ace that makes him became more and more motivated to be much more stronger than before so he can protect everyone.
2. Zorro : He lost his rival-I'm not sure how Zorro see her- (Kuina), and want to fullfiill her dream.
3. Nami : she lost her adopted mother (Bellemere).
4. Ussop : He lost his mother.
5. Chopper : Lost his father figure ( Dr. Hiluluk).
6. Robin : lost her mother and her entire island.
7. Franky : he lost his teacher and father figure (Tom-san).
8. Brook : Lost his entire crew and even his own life(hehehe).