My Beautiful Dark Twisted Fantasy

It had finally happened! Rainbow Dash was accepted to the Wonderbolts' main flight team! She was so excited, she had to tell all her friends, she had to tell Twilight-

She stared in horror at the obese body that lay in a pool of its own filth. Rainbow recoiled as she stench hit her nose.
"What-No! Twi! Gotta… Get… Help…" Rainbow's movements became slower, clumsier as her mind relinquished control of her body.

"Oh Celestia, I don't feel so good…"

Rainbow screamed internally as she lunged at the brainless ball of flab that was her friend. She splashed down face first in a puddle of liquid shit, and couldn't help but taste a little that landed on her tongue. It was... Weirdly good...

Her mind was torn apart as she gulped down the brown filth, which still contained Twilight's mind and thoughts. Only the strongest emotions could be absorbed, however - Anger, hunger, lust. Who was she angry at? Lightning Dust! Rainbow's mind recognized that name and accepted it as her own. Hunger for food, lust for anything willing to touch her filthy body. Her chins doubled as her belly expanded, causing the suit to creak as she lost all control over her mind.

The colors of her mane began to fade, changing to a soft blonde while her body turned a few shades lighter. Finally, the bulk of the shit was ingested, and she took a loud burp as she licked her dirty face.

Rainbow Dash was gone. In her place, Lightning Dust let off a brassy fart as she stared at the remains of her filthy meal and the pony who created it.

"Princess Twilight? Looks like she took a few lessons from the ol' LD!" She playfully slapped the mindless body's belly, eliciting a fart from the other end, "Sexy bitch! Woo!"

"Um," Fluttershy said, knocking on the open door, "Miss Lightning Dust? Wh-what are you doing here?"