A/N: As requested. ^^
So Hiro thinks he's too skinny and wants to put on some weight.
Baymax agrees to help him watch his progress and in the process of drinking protein shakes and eating a more balanced diet, Hiro discovers something pretty interesting… he likes gaining weight. His friends are amused but concerned by this, Baymax is the latter. One day as Baymax has a holographic tape measurer around Hiro, having again trying to dissuade him, Hiro looks down and smiles at him: Pretty sure I'll be as big as you, eh? Baymax meets his eyes, blinks and rises.
Hiro, I can only support up to 1000 pounds: He says.
I'm only nine-hundred-ninety-nine pounds, I can still increase your weight threshold if you hand me my tools.
Hiro, you sold all your tools for food.
O_O
…
Big Hero 6 is flying to stop Yama.
Hiro…: Baymax's voice is ragged and static-sounding from exertion: I cannot… BREATHE.
Hiro: Nonsense! Give me your flight suit, I'll carry us.
Hiro eats another sub he saved for just such an occasion.
Baymax, eyes going haywire: Cannot… support weight!
They fall into the ocean.
