Ever since Luffy had that phone conversation with Big Mom, challenged her, pissed her off, ate her candy, and threatened to take Fishman Island. Ever since Big Mom said she would get her revenge on Luffy and his crew. Not to mention that after the she was like come on over to the New World brat. So why would she go Sanji in particular? 1.) Both Big Mom and Luffy are obsessed with Food. 2.) Luffy ate her candy. 3.) Since Big Mom is obsessed with Food and she knows food is important to Luffy; so what better way to get revenge on him on than taking his cook. He stole all of her favorite candy so she will want to hit him were she thinks going to hurt. 4.) I have a hunch that she either collects cooks like Wapol or goes through them like crazy by that I mean she: A. She eats them if she is displeased with their cooking. B. She works the cooks to death; cooking for Big Mom is that physically demanding. It's possible to that she doesn't go through cooks like crazy but since we've seen her eat her own crew for nothing and know how much candy she demands. 5.) Maybe it's just me but when a character does something like Luffy did and challenged someone like that honestly he's not ready yet to make good on his threats yet. Generally a character can get a dose of karma eventually, after doing something like Luffy did. I don't think that Luffy is ready to take an Emperor down all by himself. 6.) It place Sanji and possibly other Strawhats in a position were they can possibly trick Big Mom and Kaido to go to war with eachother. 7.) Big Mom may have heard of stories about Sanji's cooking and probably would have gone after him anyway. Possible Scenarios 1. Sanji and his group right now escape and Sanji plus maybe others like Chopper too get captured later. 2. Sanji and co. get captured right away and Sanji has to cook for big Mom or she'll eat his nakama. It's something like The Arabian Nights or the Nightingale but with no wining the bad guy over and instead helping to destroy them. If you guys can remember myths like that tell me because I can't remember a.t.m. 3. Only Sanji gets captured or Sanji and Chopper get captured either so the others can escape. Or Sanji makes a deal with Big Mom so the others can escape. I think Chopper would be interesting because of the whole herbivore Zoan thing. 4. ( This is my favorite as of now.) (After a minor exchange of blows). Sanji and his group see what is happening back in Dressrosa. Things look dire they know this because Brook can use his astral projection to see what's going on inside the bird cage. Big Mom's crew has a way/ability to help take down's Doflamingo's Birdcage and web. However there's a cost. Sanji and whoever else will help bring Big MoM and Kaido to war in French Resistance/ revolutionary style. Maybe we'll get to see skills that both Sanji and Robin have learned during the time skip since they're train was both by revolutionaries. 5. Sanji may not get captured but I think Big Mom will target him because of the food obsession Luffy and Big Mom share. Outcomes/ Issues Maybe we will finally get to address Sanji's self sacrificial areas. On one hand that can be selfless and admirable however Sanji often seems too eager to do so sometimes when another solution could have been found. Luffy noticed this at Baratie and Drum. We also saw that at the end of Thriller Bark we see that Sanji could get another cook. He just did again when caught by Doflamingo he told them to go and Nami and said "we would never..." Not only that during the time skip he still called his dream stupid. If Sanji and his group do get captured it won't be because they are weak or anything.