He hadn’t realized at first.
His stomach was already bloated from an entire two liter of diet coke, sloshing and bubbling away, and when Sonic offered him a roll of candy, he popped four off the top, rolled them around in his mouth, then swallowed.
Unfortunately, all the warning he had was Sonic’s manical grin before his stomach absolutely ballooned. The bubbling increased tenfold, and he could actually see his gut expanding by the second, soda and foam pressing out, out, out, straining his skin and forcing out multiple belches as the chemical reaction in his gut attempted to get out any way possible.
Sonic set a hand on his stomach and pressed down hard, forcing out another burp as Shadow sprawled out, bloated gut wobbling above him like a separate being, at least four times bigger than it had been mere minutes earlier.
“You’re huge.” Sonic said, tiptoing his fingers over Shadow’s taut tummy before placing a kiss in the very middle. “You’re a pig, and you like it, don’t you?”
Shadow’s flushed face was akin to agreement as he squirmed from the pressure inside him, hiccups escaping his lips.
“And you’re all mine, to stuff and bloat up until you can barely…” Sonic ran his hands over Shadow’s gurgling gut, “Fucking…” He sloooowly flattened his palms, kneading the taut flesh and eliciting a hiccup, “Move.”
Shadow tried to lean forward, but his stomach was just too big, forcing him back. Sonic crawled up, straddling his legs over Shadow’s massive belly before holding up another mint.
“Those burps should have freed up some space. I know you want more, don’t you?”
Shadow swallowed, peppermint taste still on his tongue, before nodding, and Sonic set the mint on his own tongue before sliding down unto Shadow’s chest, passing it through a sloppy kiss and watching as his gluttonous lover swallowed down another bloating mint and felt his belly begin to expand even more.
