In Canterlot Castle:
Princess Celestia is in the class room waiting for her new student Twilight Sparkle to enter the school. The thing is that Twilight Sparkle reminds her so much of her old student Sunset Shimmer. The reason why because like Sunset, Twilight has really strong magic and need to contain that magic through focus studies.
Then a unicorn mare named Raven comes in.
"You're highness Twilight is here to see you," Raven announces.
"Yes thank you Raven," Princess Celestia replies.
"Princess were you thinking about her?" Raven asks worried.
"Yes I was," Celestia answers sadly.
"I know it was hard for you since we found out, Sunset Shimmer was a great student," Raven says.
"I know she was, but I still wish I knew what she was doing in the throne room," Celestia replies sadly.
When Celestia learned what happened, she became heartbroken when she learned that Sunset Shimmer was in the throne room on the night of the fire. The guards inform her that they saw a bright light in the throne room and smell smoke and hear broken glass coming from the throne room. When they got in the room the place is completely burned to a crisp. They also see that the magical mirror protected itself with a force field and can protect any pony who was within range.
One of the guard was able to find the other half of Sunset Shimmer necklace which made tears coming from Celestia's face. She was able to recognize right away that this was Sunset's necklace and knew she was in here, but didn't know either she started the fire or saw some pony else did it and tried to put it out. The only thing she know that something terrible happened to Sunset Shimmer but she didn't know what.
After cleaning up the mess a few weeks after the fire, no pony who was in charge of the search weren't able to find her body. This made the princess believe that either she made it out of the fire or her body was too burned to be identified. All she know is that Sunset Shimmer is gone and will have to break the news to her family.
After telling her family the news they were heartbroken just like Celestia and wonder what she was doing in the throne room at night. They even believe that Sunset wouldn't do something like this. Celestia even showed her the half of necklace to give, but Sunset's mother think it is best for her to have it.
After the incident, Princess Celestia got a new personal student named Twilight Sparkle and currently waiting for her to teach her magic, Twilight reminds her so much of Sunset that she sometimes get teary every time she leaves after her lessons.
"Princess," A little filly's voice calls.
Princess Celestia turns to see a small filly with lavender fur, dark blue hair with a magenta and purple streak on her mane and tail, and purple eyes. Her cutie mark is a six pointed light magenta star with 6 sparkles on it and 5 small white 6 pointed stars with it.
"Good morning Twilight," Celestia says happily.
"Good morning Princess. What are we going to do today?" Twilight says happily.
"Well I think today we should start by working on some new spells today," Celestia answers.
"What kind of spells?" Twilight asks.
"Well maybe we can start with the transportation spell," Celestia suggests.
"Okay, I tried doing that spell but I can only do it for a short distances," Twilight says.
"That's alright once you learn how to control your magic you can use it to travel to farther distance," Celestia says.
"Okay then let's get started," Twilight says then starts to go to the other room to start her lesson.
Princess Celestia laughed a little because Twilight is so eager to learn about magic. Then become sadden because Sunset Shimer was as much eager to learn about magic as much as Twilight does.
Celestia then goes to the other room and Twilight notice that Celestia eyes are getting watery and don't know what is wrong that is causing to cry,"
"Princess are you okay, you look like you're crying," Twilight asks sadly.
"Oh it nothing," Celestia answers and use her hoof to get rid of the tears.
"Are you sure?" My mommy told me that if there is a problem it best to talk about it. But if you don't feel like it right now that's fine too," Twilight explains.
"I'm alright Twilight it just… you mind me so much of her," Celestia answers sadly.
"Her?" Twilight says questionably.
"Oh I'm sorry about this," Celestia says.
"It okay princess you don't need to tell me if you're not ready," Twilight replies.
"I do want to tell you but I'm not sure how you will react," Celestia says.
"What do you mean?" Twilight asks
Celestia hesitated at first, because she isn't sure if she is ready to know but she really want to help. She then took a deep breath and starts to explain everything to Twilight
"To be honest I used to have another student before you started your studies with me," Celestia answers.
"Really!" Twilight says surprisingly.
"Yes her name is Sunset Shimmer," Celestia says.
"Sunset Shimmer? Do I know her?" Twilight asks.
"No you haven't," Celestia says.
"Do you think I can meet her?" Twilight asks happily.
That really surprises the princess that she want to meet her other student she is much eager to learn magic as much as she does,"
"I'm afraid you are unable to meet her," Celestia says sadly.
"What do you mean?" Did she graduated or she moved away?" Twilight asks uncertain.
"She mysteriously disappeared," Celestia answers sadly.
"What happened?" Twilight asks.
"You remember the fire that happen before you started your studies with me?" Celestia says while looking at her.
"Yes," Twilight answers.
"Sunset Shimmer was inside the throne room when the fire happened," Celestia explains.
"Oh no!" Twilight says sadly.
"But I don't know where she is," Celestia says.
"What do you mean?" Twilight ask
"Well after the fire the pony expiations look all over the throne room and only found half of her necklace but not her actual body," Celestia explains.
"Do you think she's still alive?" Twilight asks.
"I can only hope Twilight," Celestia says sadly.
Twilight can tell that Princess Celestia is very sad about her student and wish there is a way to help her then an idea came to her, "Don't worry princess maybe I can find her and if I see her I can tell her that you really miss her."
Celestia becomes happy that Twilight wants to help then says, "I appreciate the help Twilight and maybe when you are a bit older and do better with you magic you can travel to many places but for now let's get started with your lessons okay,"
"Okay," Twilight replies.
With that Princess Celestia starts to teach her some spells like the teleportation spell, and a few transformation spells on objects.
Celestia is very pleased with Twilight progress and her magic grows stronger every day and she is proud of her of her success.