Every once in a while I reveal my amazing head from my magical tortoise shell. When I do, you know things are about to go down. This one time, I even saved somepony from certain doom! And this other time...
I blinked. It was pretty rad.
History
Tank is Rainbow Dash's pet tortoise. She was the last of the Mane Six to receive a pet.
Growing up in Fluttershy's house was quite the experience in Tank's life. Every day seemed to be the same: Wake up, eat, and sleep. Sure the other animals tried to involve him in their activities, but he just couldn't keep up with the rest. That's how it was for the past century or so. It all changed though when she came...
Minding his business on a bright and sunny Friday afternoon, Fluttershy returned to the house with her friend Rainbow Dash. They proceeded to display what he perceived to be a complex series of dance moves and vocal fluctuations. A great show, if he's any judge. At couple of times, he even tried to join! Sadly he has three left feet, so was left out of the great fun the ponies were having.
For some reason, Rainbow was testing a bunch of animals and Fluttershy thought it'd be great if he joined in. He politely obliged. Nobody says no to the Yellow One. Tank tried effortlessly to appeal to the Blue One, but was only rewarded with a whistle blown in his ear.
Soon enough, a race was started. Tank was unsure about this, seeing as his fearsome adversaries were all winged while he was left to stay on his feet. He knew in his hearty though that this was meant to be. This race would lead him to a better life! Maybe he'd even make a friend or two! Hours went by, or at least they seemed to. All the other racers were much further ahead, leaving Tank completely alone. He hadn't felt so isolated since his days as a hatchling in the Underwater Gardens of the Subterranean Octopi.
Did they forget about him?
Was this a trick to get Tank away from them?
Did the whole world blow up, leaving him in a desolate wasteland?
...nah. That'd be silly, he reasoned.
Soon enough, he found the young blue mare, also by herself. What was worse, her feather flapper was trapped beneath a rock! Knowing the rock was no match for him, considering his time spent in the Rock Flinging Rock Slinging competition of 1908 in the Bermuda Pentagon, he started to release the swift flyer from her imprisonment even while she berated him. Upon escaping what most certainly would have spelled her doom, he offered up the bandages any Turtle Scout would carry with him and proceeded to carry the young ward to her anxious friends at the finish line.
As much as she may have criticized him before, Rainbow showed a special interest in her new found friend and asked him to join her as her animal companion. Upon agreeing, the Mystical Magician known as Twilight Sparkle created an ingenious device to allow Tank the ability to soar in the air with his faithful and most dear friend in the world.
To this day, you can see the duo shooting their way across Ponyville skies. One practices her fanciful tricks as to hopefully join the elite flyers, the Wonderbolts. The other practices his tricks because he finds it fun, and it also brings a smile to the faces of the ones he loves.