An obscenely short and silly story I did as a request from :icon coolboy21: who insisted I do something like this. Consider it a sort-of sequel to my Knuckles story.

Sonic the Hedgehog hadn’t seen Rouge the Bat in a while, nor Knuckles for that matter. That being said, he was surprised to receive a package coming from both of them with a strange note.
“Dear Sonic,” it began, “I do hope you haven’t been worrying yourself sick over me and my precious Knuxie Knuckles. The two of us are doing just fine, to say the least. In fact, we’re getting to know each other quite a bit lately, and having so much fun doing it. So I wanted you to get a taste of what we’re feeling right now. In this package is the result of that little excavation I went on a little while ago. I did some experiments on my findings and you seem like the perfect candidate to look over the results! I think you’ll be pleased. The best from these two lovebirds, Knuckles and Rouge. P.S. Why don’t you share some of this with that pink friend of yours?”
Sonic almost cringed when he realized that she was talking about Amy Rose, Sonic’s self-proclaimed girlfriend. Sonic thought her a sweet enough girl, but mostly found her overbearing as she chased him up and down the city streets on very one-sided dates. For the life of him, Sonic couldn’t think of why Rouge would want him to share his package with someone like her.
That being said, Amy was currently resting on Sonic’s couch. He figured that he’d oblige Rouge’s letter by sharing whatever Rouge sent him.
“So,” Amy asked cheerfully, “What did Rouge send us exactly?”
“I was about to find out,” Sonic replied, unwrapping the package carefully.
I still don’t know why Rouge would want me to do this with Amy, Sonic thought. We’re not exactly on bad terms, but she’s just so…clingy! What would she want me to do with a girl like her?
“Well, let’s see! Let’s see!”
“Hold your horses there. I’m about to show ya.”
Sonic threw away the paper wrapping to reveal what seemed to be two ice cream buckets.
“Hm? Ice cream?” Sonic asked. “Why’d she send me this?”
“Dunno, but it looks yummy!”
“I guess. You’d think it would’ve melted by now, though.”
“That’s a little weird, but hey! Ice cream party!”
“Do you see what I’m saying, Amy? This can’t be ordinary ice cream. It’s still chilled! No way it could have stayed that way in the mail!”
“Well, it’s not like it’s unsafe or anything! Rouge wouldn’t send us something like that, would she?”
“Maybe…not…”
“So let’s dig in! I’ll get us some spoons.”
Sonic stared at the ice cream cautiously as Amy rummaged through the kitchen for spoons. His head was spinning with any possible reason why he got this strange ice cream.
“Found ‘em,” Amy called from the kitchen, running back to Sonic with spoons in hand.
“Oh! Okay…”
Sonic hesitantly took the spoon from Amy and took one of the ice cream buckets. Amy took hers and the two of them opened the containers at the same time. A sweet vanilla scent wafted towards their noses, and suddenly, Sonic’s apprehensions were overcome by how nice he thought the ice cream smelled.
“Not bad. Maybe this stuff is as good as it tastes.”
“Yeah,” Amy proclaimed. “Let’s dig in!”
“Why don’t we just be a little caref—”
Before Sonic finished his sentence, Amy had already taken a big scoop of ice cream and eaten it.
“Or not.”
“Mmm! It’s really yummy!”
“Is it?”
“Yeah! Come on! Have some!”
Amy started taking more scoops from her container, eating each bite with savor.
“At least it’s good, I guess. Hm?”
Sonic noticed that despite all of her scoops, Amy’s cup of ice cream seemed to remain full, never going down.
“What the…? Whoa, Amy!”
“Hm? Whuh?” she muffled through her next scoop, not noticing that her belly was now bulging through her dress.
“Your belly! It’s…”
Amy ignored Sonic and continued eating. All the while, her belly started getting bigger and fatter before Sonic’s very eyes. His eyes were then drawn to her lower extremities. The gap between her thighs was getting smaller and smaller as they started squishing and pushing against each other as they grew. Her butt began filling out the back of her dress, eventually peeking out and revealing her pink panties that were now serving as a glorified thong for her growing buttocks.
Her entire outfit began to tighten around her swelling body. Her dress began rising like a curtain, showing off her flabby belly and lovehandles pouring over her thighs as thick as logs. Her boots had long since burst, hardly being able to contain her fat-gaining legs.
Amy’s face started growing multiple chins, practically sinking into the rest of her pudge, while her breasts started taking on weight, becoming large water balloons over her even larger belly.
If Amy had at all noticed what was happening to her, she didn’t care. This was made clear as she took a break from her ice cream, setting the cup in between her massive boobs. She panted happily with her tongue sticking out.
“Man, that stuff is delicious! What do you think, Sonic?”
Sonic couldn’t reply. He simply stared at how fat Amy had become. She finally took notice of her changed and examined herself.
“Boy, did I pig out! Look at me. I’m a real hog of a hedgehog! My belly’s hanging out and my butt’s gotten so soft! It feels pretty good!”
“Looks that way…”
Amy looked to see Sonic staring at her lovingly.
“What was that, Sonic~?”
“You…you look beautiful, Amy! I don’t know what was in that ice cream, but it made you hot!”
Amy giggled at the irony of that statement. She hefted her soft breasts and shook her whole body, making it jiggle. Sonic shuddered with excitement.
“You really think so? Well, why don’t we get you that way too?”
“Huh?”
Before he knew it, Amy fell right on top of Sonic. He grunted at the sudden feeling, but found himself very comfortable with all that Amy fat pressing down on him.
“I’ve got you pinned now! So…why don’t we even this little playing field?”
Amy grabbed Sonic’s ice cream and spoon, took a gigantic spoonful and shoved it into his mouth, keeping it there until he swallowed.
“Mmm! Amy, that stuff is really good—mmph!”
He squealed as Amy forced another scoop into his mouth, and another, and another. She wouldn’t let up as he kept a quick and steady pace of feeding him scoops of this special ice cream. Underneath her flabby blob of a body, Amy could feel Sonic changing.
His belly began pushing up against her own as it distended and was practically inflating with ice cream. With a free hand, Amy reached behind Sonic when his butt became big enough. She squeezed the soft, furry mound hard. Yet instead of a cry of pain, Sonic felt pleasure at the squeeze. His thighs thickened enough to intertwine with Amy’s, and the two shifted their large legs around each other’s, which felt like sifting through dough. Amy kept up the habit of feeding him, squeezing his butt, blowing into the cleavage made from his newfound pair of moobs, and massaging his belly, keeping it soothed and digesting to make room for more ice cream.
By the time Amy decided to take a break, he was twice as big as she was, still pinned under Amy, and extremely happy.
“How do we feel, my blue, bloated beau?” she asked, playfully cupping and squeezing his moobs.
“Amazing…I’ve never felt so good in my life.”
“I’m glad.”
“And…I never saw it until now…but you are just absolutely beautiful.”
“You really think so? I have put on a little weight recently?”
“No kidding, but little is right.”
“What do you mean?”
“Look at you. Your clothes still fit and you can move around pretty easily. You haven’t gained much at all! I’m gonna have to feed you some more of that ice cream and make you as stuffed as a Thanksgiving turkey.”
“Sounds like a plan to me.”
“Besides…I think it’s time you and I got to know each other…”
Sonic lifted his flabby, somewhat useless arms and landed them right on her butt, squeezing pleasurably as hard as she had before.
“…intimately, at that.”
“Oh, Sonic,” she moaned as she squeezed his lovehandles. “Let’s.”