User blog comment:Awaikage/Chapter 807 - Elephant Jack on the Elephant's Back/@comment-4899461-20151119160532/@comment-26803131-20151120195106

Caesar will be the next Straw Hat. Robin forced her way into the group, he'll end up staying for 3 reasons.

1. He's a prisoner and has no choice

2. If he's on his own he has to worry about Big Mom (who Luffy is already battling)

3. Luffy will forget why he dislikes him and says aren't you a part of the crew already

Or Law will deal with him