It wasn't very long before they arrived at the magnificent castle of Canterlot. They entered through the front door, walking past two royal guards who just glared at Dragon Charge. He didn't pay them any mind.
He and Luna walked through the front hallway, and then he noticed two of Luna's guards carrying Critic away. Before Dragon could speed after them, Luna stopped him.
"He shall be okay.", she said. They continued walking, and after a moment of silence, she spoke up again.
"It's not as easy as you think, young one." Dragon gave her a confused look.
"Being a princess, I mean. We have our trials and suffering just like you do.", she stated.
"What, deciding which crown to wear every morning?", Dragon sneered. Luna's face grew very sad and far off, as if she were experiencing a great tragedy all over again.
"Have you heard of the story of Nightmare Moon?", Luna began. She told him the story of her fall from grace, her imprisonment, and how she was reunited with her sister.
"But the guilt never leaves. I often wonder what I could have done differently, if maybe I had just followed the advice of my elders, maybe things could have turned out for the better."
They stopped at Luna's Tower, in the study room. "I am giving you the same chance I once had many years ago.", Luna explained. "You can let your hatred for the world consume you and lead to your eventual downfall, or you can study under me, learn to control your magic, and use it for the greater good."
Dragon thought for a moment. "And if I don't?" he asked.
"Then I have no choice but to place you under arrest and let the jury decide your fate. The citizens of Canterlot are pretty bloodthirsty, so I would not advise it." She warned. "Become my pupil, and you shall live in this castle until you are ready for... greater things."
Just then, Critic walked into the room, escorted by the royal guards.
"Hey Dragon, you wouldn't believe this! They've got a soda fountain! The decor's a little much, but eh, what can ya do?" Dragon smiled at his friend, then turned back to Luna.
"If I agree to this, he stays, too. He is my friend. If you're taking me, he comes with."
Luna smiled. "Very well then. I hereby declare you my pupil."
Over the next few years, Dragon studied all sorts of magic, from combat to levitation, to defensive, to making little hats appear on somepony's head, all under the guidance of the Princess of the Night.
Every now and then, he would dream about his mother, but for the first time, he truly felt at home in this castle.
Luna was a very no nonsense teacher, but on Dragon's days off, she would tell him stories of Starswirl the bearded and the great unicorns of her youth. She would tell him of her sister and the days before Nightmare Moon when they were extremely close. Then, one night, she asked Dragon of his family.
"I don't know them. My mother left this note in my basket when she dropped me off at the old orphanage."
Luna read it, and a wave of sadness came over her. "I'm sorry. It must not be easy to feel alone."
Dragon smiled. "I'm not lonely. I have Critic."
"I suppose you're right" The Alicorn answered him.
"...and you.", Dragon yawned.
Luna smiled. Whatever lied ahead, Dragon knew he could get through it. Sure, he might have had a bumpy start in life, but with the love of his friends, he knew that anything was possible. He walked to his room, lied down, and let himself fall sleep.