Elke prompted me to write the head canon I have for what could happen to Sanji when he finds All Blue

Sanji's never made someone sick with his food, but his son is really unwell and it gets worse with every meal that Sanji manages to get into him. He doesn't understand it. The kid isn't running a temperature and he's happy to drink water but the more he feeds him the sicker he gets. He's pale and clammy in Sanji's arms.

He can't really be blamed, he's only been a father for three days. Though the child in his arms looks more like a toddler than a newborn. That's because his son isn't entirely human, the god had said he was a demi-god, half Sanji and half Neptune's own offspring.

He'd expected a great deal of different things when he got to All Blue but this was not one of them. There was a god living there, a god guarding the way. It was prepared to kill him, to kill them all, but he'd convinced the god Neptune just how worthy he was of being part of All Blue, of seeing its wonders. So the god had gifted him a son, or... cursed him perhaps.

The little boy looks just like Sanji, only younger. His eyes seem a little different and he's already able to crawl. Chopper had pronounced him healthy when he was first brought on board, clever too as the kid caught the stethoscope before Chopper could listen to his heart and laughed right down it making Chopper's ears ring. Now though, he's not so healthy.

"Chopper, he's sick." Sanji finally admits, heading to the infirmary. Great. He's barely had the kid three days and he's already nearly killed him.

Chopper looks the kid over and seems to agree, gesturing for Sanji to sit down on the examination table with the miserable infant in his arms.

Sanji looks down at his own younger face, pinched with unhappiness. Chopper runs the stethoscope over the little boy's back with a frown. Sanji hasn't even thought of a name for him yet, though he's been calling him 'little duck' because of the stuffed toy he'd latched onto the moment that Nami had presented it to him. His apathy about holding it today was one of the things that tipped Sanji off to his unwell state.

Chopper frowns and pulls the buds out of his ears and places his own ear flat on the child's back.

"He... doesn't have a heartbeat. I can't hear it anywhere." Chopper says after a few moments longer.

"What?" Sanji blinks in confusion. He holds up the snuffling, complaining and very much alive infant and presses his own ear to his chest.

No heartbeat. None at all. And unless he's making noise Sanji doesn't hear breathing either, just... the sound of the ocean. Like he's put a seashell to his ear. He holds the child up, his eyes wide in wonder. The kid isn't human at all.