User blog comment:Raptor of Love/Flamingos Cards/@comment-4605926-20130303194502

The club seat was given to Trébol. I truly wonder why Oda decided specifically not to introduce the spade seat fella. Perhaps something especially unique about him.

I'm guessing that each of the chairs go to allied pirate crews' captains and not directly to any underlings of Doflamingo from his own respective crew. The fact that the heart seat was initially meant for Law could emphasize this theory. This implies that they are renowned New World pirates that are not to be meddled with and are a force to be reckoned with. This also supports the fact that they are not intimidated by Doflamingo and nor does he regard them lowly.

I'm also guessing that no one will actually eat the fruit until much later because Doflamingo might be using it as a trump card to lure Luffy and sabotage the alliance.