“Look… Cas.” Gabriel starts slow, because he topic at hand warrants it (the sheer caloric overload his brother was slogging through warranted it, too). “This is a case of ‘just because you can- doesn’t mean you should’.” Gabriel loved eating just as much as the next semi-fallen angel, but this- well. Gluttony didn’t even begin to cover it anymore. “I mean- just look at yourself! This is all from one binge!”
Castiel looked up at Gabriel. It seemed to take him a moment to process exactly what had been said to him. He opened his mouth to reply, but before he could, he belched, so loudly it practically rattled his wings.
"I don't understand," he said, and reached languidly for a burger.
Gabriel fought not to roll any of his eyes, keeping the "concerned big brother" look firmly in place.
"Let me lay it out for you," he said patiently. "You...are...eating...too...much, Cas. Way too much. Look at this!"
He reached down to put a hand on Castiel's stomach. There was sure enough of it; he had his pick of places.
Castiel had built himself quite the comfy little nest in his bedroom. Snuggled in among the pillows and blankets along one side of it, he was propped on a hip and an elbow, watching TV and steadily feeding himself. His belly, which represented something like six or seven hours of steady, constant gorging, filled most of the rest of the space, round and bloated with fast food, soda, and a healthy helping of baked goods. One wing was folded lazily over it.
Castiel, chewing, looked down at it, but rather than the shock that Gabriel had expected, just gave it an almost affectionate pat. His hand stayed on it, rubbing, and he groaned as he used his other hand to cram another burger into his mouth. Gabriel tried a different tack.
"You're getting fat," he said, delivering a sharp pat to Castiel's burgeoning bubble butt, then a poke to one of his love handles. That...may not have had the intended effect either, considering Castiel's feathers fluffed up.
"Hope so," Castiel said after swallowing, then belched again.
"What?" Gabriel asked blankly.
"Bigger I get..." Castiel lovingly squeezed his very overfed gut and slurped soda. "More I can eat."
Gabriel crossed his arms. "What do the Winchesters think about this?"
"Mmph." More fries for Castiel. "Dean brought me this."
He gestured to the food. Half remaining, half wrappers.
Gabriel was silent for a long, long second, before asking, "What am I supposed to do?"
Castiel seemed to honestly consider that, before blinking up at Gabriel, and handing him a miniature apple pie. The kind you got, wrapped in wax paper, at a burger place.