Celestia woke up and immediately became a bit frustrated. Unlike her sister Luna, she enjoyed the feeling of relaxation granted to her when she slipped into that blissful state of unconsciousness. Both of the sisters were aware that it was entirely optional for them. Since they were imbued with the power of heavenly objects, and that is an immense responsibility that didn't leave much time for snoozing, King Sombra had permitted them to alter their biological forms. This was no small favor on his part. Under his rule, the use of any consciously controlled magic was strictly regulated, and in some cases, such as pegasi flight or until now tampering with the inner being of any creature, outright forbidden. But since the two sisters were his prized pupils, he agreed to condone it in this particular case.
However, the spell they cast upon themselves did not remove their capability to sleep, only made it optional. Celestia still preferred to do it, as she found it therapeutic.
Luna, on the other hand, felt that the night was neglected enough as it was, and since she certainly wasn't about to start sleeping during the daytime either she decided to give up the habit altogether. This had actually turned out very well for both of them, as Luna had discovered a latent ability during the lonely moonlight vigil she kept over the castle: she could enter the dreams of others, and not only could she change the dreams entirely, she could also use the dreams as a sort of channel into their mind. Even though the only thing Luna could use the latter ability for was figuring out what happened to the person during the day, it was still intimidating enough to legitimately frighten anyone who knew about it.
This included Celestia, whose only thought on the matter was that Luna didn't quite understand the concept of privacy, although she did enjoy that the two of them were able to play around in her dreams, which is what had just been happening before the hills of candy had been rudely dispelled by a ringing alarm.
"Curious, for I thought this day was Saturday." said Luna as she quickly materialized from her sister's dream.
"It is." replied Celestia in a gruff, grumpy voice. "Sombra didn't let either of us take the day off because somepony put a cockatrice underneath his pillow, remember?"
"Oh. Yes. Verily. My apologies for that."
"And can you PLEASE stop using that 'traditional royal voice'? It drives everyone nuts."
"Sorry." Luna replied, instantly reverting to her normal speaking voice. "Is it really that annoying?"
"YES. Now come on. We have training to do, remember?"
"Okay, okay. Yeesh."
The pair exited their quarters and headed for the training room.
"So what is it today?" asked Celestia through gritted teeth.
"Whoah there!" Sombra laughed, and suddenly directed his gaze toward Luna. "Candy dream get interrupted again?"
Luna nodded.
"Well, Celestia, I'm sorry your alarm coincided with a dream you liked, but I'm going to teach you something very important today. You can either make this miserable for all of us or, more preferrably, realize that you don't need to get a sugar high every single night. I know I've said this a lot of times in which it's truth was highly debatable, but what I have to teach you today is crucial for you to learn if you are ever going to become the heirs to the throne. Any questions?"
"Yeah, I've got one." said Celestia. "Aren't you immortal? Why do you need heirs?"
"Because if it is possible for something to happen, it will happen eventually. As much as I hate to admit it, I don't know everything, nor can I survive any situation. If and when the Draconequi invade again, or the Alicorns fight their way here to Tasit, or some other factor I am not currently aware of intervenes, my life will be in danger. If luck decides to collect the massive debt I owe her for helping me all these years, I will need some capable leaders to take my place. That is why I am training you."
The sisters looked at each other in realization. They had lived the whole of their short lives in this castle, being served by the butlers and mentored by King Sombra himself, but had never really stopped to question why.
"And for your training, you must first learn what lies beyond the palace. Luna, I know you've always wanted to know this, and Celestia, I'm actually quite shocked that you didn't. Either way, you're both about to find out."
Luna began listening all the more intently. Unlike her sister, who had never really been interested in anything beyond the places she regularly went to, Luna often wondered what the world outside was like. She had asked the castle servants about it, but they only gave small tidbits of information. All she really knew was that there was a sea to the east and west and that the palace was in the middle of the city. She had even only learned the latter fact when she walked along the ramparts on the outer wall and looked at the other side. But anyway, she was about to be told the truth, and almost squealed in anticipation.
Now, the servants have probably told you something about me being a conqueror who united the whole world under my own rule, regardless of whatever they thought of my skills as a ruler. This is not entirely true. There are actually a few areas still independent, but they're completely harmless. These are located- oops. Forgot to activate the map.
As he said this, his horn started to glow a very dark shade of blue, which was also the color of uhis eyes. In turn, a lever on the far side of the dimly lit room took on the same glow, and was pulled. Luna could not help but notice how much his magic's color contrasted with his white coat and silver mane.
Suddenly, the wall behind him lit up with an image, and he moved out of the way so the two fillies could see it. It was in the shape of a five-pointed star, with all different colors on each of the points. Luna could only assume that this was a map of the world's land mass, and that each of the differently colored points was a peninsula.
"Now, we are currently at the exact center of this map," Sombra gestured to the bright green area covering all of the land that wasn't part of one of the five peninsulas. "In this palace at the center of my capital city, Tasit. The environment here consists mainly of grasslands, with a few deciduous forests here and there. The population consists mainly of earth ponies and a few pegasi, with the exception of the cities, which are inhabited almost entirely by unicorns like myself.