Zoro is a cambion, which means he feeds on sexual energy. A small crew like the Strawhats, its not normally enough to keep a cambion satisfied, but Sanji happens to be an abnormally sexually driven cook so it usually works out okay for Zoro. At least, it works out alright until Sanji finds out that Zoro's been taking energy from him through his dreams. For Sanji, he's trying to wade through the confusing mess of emotions for a certain marimo after a surprise kiss on the battle feild. It's not easy to do on a normal basis. It certainly isn't any easier when the man he has deeper feelings for is a cambion. Then everyone learns how important it is to keep their local cambion fed, for if they don't, someone might get eaten. literally.

"You turned," Adaar said, "into a fucking dragon." It was good that she said it, because someone should, and to be honest the Bull was feeling a bit beyond actual words at that exact moment. "A small dragon," Dorian said, as though this was somehow relevant. He was quite a small dragon, it was true—he stared down at them now, but most of that height was the arch of his neck, the curve of it covered in shimmering black and gold scales. "A small dragon! Who saved your life!"

Sid cradled the weighty feeling of his abdomen in his hand. It wasn’t round yet, he could just feel the developing firmness under his belly button, but it would get there, and soon. Sid knew it would. Geno had triggered something in him and there was no undoing it. Sid would have to ride this wave out.