“So, Ben likes to push his weight around does he? Lets see what it’s like when someone else is the big boss around here,” Gwen said to herself as she studied the spell on the computer more closely. The spell had two different powers, it could add ft to every inch of her body or only place it on one area. Gwen thought about becoming one big butterball. It would be interesting to be so big all over, but anyone could get fat with enough eating, only magic would allow her to have a slim body and huge assets. Gwen chuckled at the thought of her holding a pair of breasts bigger then her head and then growing a butt that dragged on the ground. It would be fun, for sure, but that didn’t mean that she was going to forget about becoming a bigger girl all over. For now, she’d only expand one part of her body, but later, she’d even it out with the rest of her body.

Outside, a bright neon green flash that Gwen recognized followed the sound of a timer going off. Gwen looked outside and saw Ben dusting himself off, while the thugs he had been fighting ran for their lives.

“Another victory for Ben 10!” Gwen rolled her eyes at hearing Ben’s victory cry. Could he be any more obnoxious? Gwen turned to the computer, memorizing the spell quickly before running outside. She was going to congratulate her cousin for his easy win and show him that he wasn’t the only person that could alter their body. She stepped out of the Rust Bucket, a big plastic grin on her face.

“Great job, Ben!” Gwen said with fake acclaim, which Ben couldn’t see. “I just wish Grandpa was here to see you thrash those thugs.”

“Yah, it’s too bad he wasn’t here to see me kick butt. Did he say when he was going to be back?”

“Don’t know, he said that he had plumber business to attend to and we should stay here until he comes back.” It was pure luck that their grandfather was off on some mission from his old days, leaving both of them alone with the Rust Bucket in the middle of the forest. Gwen couldn’t ask for a better opportunity to show up Ben and put him in his place.

“Ben, I need to show you something, but I need to set it up. Could you turn around for a minute and not look while I get ready?”

“No problem, it’ll be nice not looking at your butt-face face for even a second.” Ben turned, missing Gwen’s smile becoming much more sinister. That was the perfect set up she needed, she’d finally show Ben what a big butt looked like. With no time to spare, Gwen slid down her pants, there was no way they would be able to contain her booty after it started growing. She paused for a second and decoded to forgo her underwear as well, no need to stretch them as well. Ben kept his back turned, having no clue that his cousin was half naked behind him. Gwen placed both her hands on her buttocks as the spell instructed and quietly chanted the spell. It was all nonsense words that could have been Latin or Klingon for all Gwen knew. However, after she finished saying the last word, she felt her ass suddenly swell in her hands.

“Whoa,” she whispered as the transformation began. Her buttocks tingled as it expanded, each cheek started to swell like a balloon, retaining it’s round shape and softness. Her butt grew wider outwards, causing Gwen to nearly fall over, but she got her balance and looked behind her shoulder to see how far it had gotten. Her eyes shot open at the sight of her peachy white ass halves reaching over a foot in width and diameter, and not even showing signs of stopping. Her ass grew bigger then her head, then bigger then her body, until it looked like she had two beanbag chairs where her butt should have been. She swayed as she walked, her cheeks grazing the forest ground, but she got close to Ben and turned her butt towards him.
“Look what I got for you, Ben,” Gwen sweetly told her cousin.

“Finally, what were you doing, having a…”

Whatever Ben was going to say was muffled as Gwen pushed her ass right into Ben, toppling him over. Before he could get up, Gwen sat down on top of him, burying him under over a hundred pounds of ass flesh. Ben’s feet stuck out from under the huge ass, kicking franticly as the rest of him was smothered under Gwen’s sizzling and supple ass.

“Whose the butt-face now?” Gwen cackled as she shifted her colossal caboose on top of her Cousin. He struggled as hard as he could, trying desperately to get out from under Gwen, but her butt weighed too much. Ben was trapped until Gwen decided to get up on her own.