Tank the Dragon: Princess Celestia's Assistant

Tank had been born in a Canterlot School for the Gifted, given to a young unicorn foal as a test of his magic capability. However, once hatched, the unicorn foal did not want him. The principal asked Princess Celestia what she wanted done with him, and she decided she would take him in herself. He was taught reading and writing as a hatchling, and later learned how to send and receive letters. Eventually, he began to help out around the castle daily.

At the age of five, the princess had decided to give him a bicycle for his birthday. While he was testing his new bike, he had turned too fast on a corner and went tumbling down a small hill, resulting in the loss of his tail. The accident had made him more serious about life, and he grew into the job of Celestia's assistant. No matter what shall happen, he will always remain loyal to her.