Twilights New Pet

Twilight dragged Dash with her magic all the way to Fluttershy's, since she wasn't really looking for another fetch-the-dog round. After the explanation why Fluttershy's oldest friend was now a dog, the shy pegasus fell in love with the cute little dog.

"Who's a good girl? Who's a good girl?" Fluttershy asked Dash as she was rubbing the fluffy belly.
"So...I was wondering if you could give me some...advice."
"Advice?"
"Well...everything I need and need to know about dogs..."
Fluttershy gave her a look.
"I would have read about them but 'some dog' destroyed my library."
"Oh..oh my..."
Fluttershy stopped petting Dash and walked over to Twilight. Dash got a huge curiosity and when nopony was looking, she sneaked into the kitchen.
"Tell me what happened."
"Well...first she destroyed my working room,"
"Oh no that's terrible!"
"And today she was destroying my library when I woke up. Then we went for a walk and she ran away, fetching Opal. And she's attacking everyone she knows with her licking!"
"Hmm..well...I'd say about the destroying part, lock the doors. Going out only on a leash-"
"A leash? But...Applejack never takes Winona on a leash!"
"Twilight. Rainbow Dash is not Winona. She's trained. Dash is...well...Rainbow."

Meanwhile Dash was eating everything pet food related. The room was a mess and her belly grew bigger.

"You need toys so she won't get bored. Oh and proper food! Come on, we'll get the things."
"Thanks Fluttershy!"
Fluttershy was taking Twilight around, grabbing balls, chew toys, collar and leash. Then they were heading to the kitchen for bowls and food.

"EEEP!"

Twilight reached the door. The kitchen was a complete mess. Surrounded by several emptied bags of food lying around the cyan dog, who was as round as a ball. Twilight's jaw hang to the floor. Fluttershy ran over to Dash. This was bad. Very bad. She ran upstairs to the bathroom and returned with a bottle. She grabbed a spoon in the kitchen and filled it a bit with the liquid from the bottle. Then she stuck it into Dash's mouth.
Twilight just stood there. She..just..ate..ALL OF THAT?!?!
With the blink of an eye Dash stood in front of the purple alicorn, wagging her tail, back to her normal lean form. Twilight looked up to Fluttershy.

"How in Equestria did you Do that?!"

"Oh it was nothing. Just some fat-burner I got from Zecora. Some of my animal friends have a little eating problem." The pegasus giggled.

"Thank you so much, Fluttershy! I don't know what I would have done without you!" Twilight said, making Fluttershy blush.

"It was nothing, really. I'm sure you would have a spell to fix it."

"Hmm maybe. But since my books are shredded, I wouldn't be able to find one."

"Anyways. Talking about food..." She went to a shelf with food for puppies, grabbed a few bowls for food and water and placed it in front of Twilight.

"Thanks again Fluttershy!" Then she saw the bag of food. "Puppy food?"

"Twilight, you Do know how old she is, right?"

"She is a grown dog, or?"

"No. In fact, she is quite some time away from fully grown."

"But..the spell doesn't change the age! How old is she?"

"Well, she's older than a puppy, and younger than a grown up."

"You mean, a teenager?"

"Quite right."

Twilight froze. Sure, Dash had always been smaller than the others, hyperactive but Pinkie...okey Pinkie Pie is Pinkie Pie. Well...she Was acting like a foal sometimes..is easy to get angry, has a lot of temperament...okey, maybe she really Was just a teenager.
The fluffy thing that was nudging her front legs broke her from her thoughts. She looked down and saw how Dash was cuddling her. She couldn't help but smile and stroke a hoof over Dash's back.

"Looks like some pet really likes his new owner." Fluttershy chuckled at the sight. You could describe it as cute and adorable...cudorable!

"Oh, Twilight?"

"Yes, Fluttershy?"

"Don't you think she needs a, well, pet name?"

"Well...yeah, maybe.. I'll think of one."

Fluttershy put the collar with the leash on Dash's neck. To Twilight's surprise, Dash sat still like a stone. Well...except for her always wagging tail.

The two walked back home. It was so much easier with the leash. Dash was walking right beside her. Maybe it was a good idea to turn Dash into a dog, since she was the element of loyalty. Dogs were loyal, that's for sure, but Dash had to be the most loyal dog in the world.