Even though she'd been called in for one on one talks with her mentor before, Luster Dawn was still incredibly anxious about the sudden summons to Canterlot from Twilight Sparkle. It wasn't every day that the Supreme Ruler of Equestria asked specifically to meet with you. Luster remembered that the last time this had happened, her mentor had ultimately sent her to Ponyville to better learn about the magic of friendship.
What could be so urgent as to warrant a summons now of all times? Luster didn't know, and it made the unicorn mare with a light pink coat more anxious and ill at ease than before. Still, there was little she could do but respond to the summons and show up at the castle on the day in question.
It still amazed Luster Dawn how much her mentor seemed to tower over her. Even Princess Flurry Heart wasn't anywhere near as big (from the few times Luster had seen the crystal princess anyway). They all said that Twilight Sparkle wasn't actually as big as she appeared to be, that it was just something she did to keep up appearances. But Luster was certain she knew otherwise, why else would her mentor continue to always appear with that long, flowing mane?
Twilight simply smiled. "Luster, you really must stop worrying so much every time we meet. You aren't in trouble."
Luster blinked her orangish-yellow eyes slowly in reply. "I'm not? Are you sure there isn't something you've come to scold me about?"
"Why would I do that? You aren't a little foal who needs to be corrected," The supreme ruler declared in a friendly tone of voice as she approached her student. "I've always believed in gentle guidance as needed, but I've also done my part to give you space to be yourself. It's how my mentor raised me."
"Princess Celestia? Yes, I remember hearing about her," Luster commented. "I wish I could've had a chance to meet her in pony. She sounds like she was truly a one of a kind mare."
The alicorn nodded and bowed her head. "Indeed she was," Her tone of voice seemed to change as she spoke those words, taking on a somber tone. "She and her sister, Princess Luna, were two of the best ponies I had the honor of knowing. But even they had to be mentored by somepony: In their case was the great Starswirl the Bearded himself. And even he didn't become all wise and knowing overnight, he too had to learn from somepony. That is, of course, why I took you under my wing."
"I remember, your majesty," The unicorn slowly replied. "The day I met you was the day my life changed. You were right when you said I had potential. Even before I knew it for myself, you saw in me a pony who was capable of so many things. And it was your guidance that helped me to realize friendship wasn't a waste of time like I thought."
Twilight smiled as she lifted her head. "Yes, Luster Dawn. And that is why I wanted to speak to you today. Why I requested we meet in private as teacher and student," She turned her attention to the stained glass window displays that lined either side of the throne room. "But there comes a time in every student's life when they must surpass their master to become a teacher in their own right."
At that, Luster became confused. "But you always said life was a learning experience, that we never truly stop learning new things."
The alicorn chuckled a bit. "I did say that, Luster. Yet if you'll recall, I told you then that many of life's lessons are ones we must learn for ourselves. Even I could only point you in the right direction, I could not make friends for you because that wouldn't have helped you learn about friendship. And now, much like friendship, I believe there is something you must come to understand."
The unicorn mare stepped back a bit in concern. "What is it?" She gulped. "Y-you're not planning on stepping down anytime soon or anything like that, are you? Your reign in Equestria has been a glorious one, you've accomplished so much in so little time. Why would you want to give it all up now?"
Twilight Sparkle's smile grew brighter as she reassured her troubled student. "Relax, Luster. I'm not planning to step down from the throne if that's what you are worried about. However, much like I inherited the throne from Princess Celestia, so too must you consider the possibility that I won't always be around to guide you. Just as the sun must inevitably set to make way for the night, so too will my time as supreme ruler come to an end. The sun will set on my time sooner or later."
Luster gasped! "You... you're not dying, are you?! I always thought alicorns were immortal!"
The supreme ruler could only somberly reply. "Though we do tend to live long lives, even we alicorns are not immortal. Princess Celestia and Princess Luna's passings should have taught you that," And she explained. "No creature is truly immortal. From the day we are born or otherwise brought into this world, it is inevitable that we will grow old and eventually die. That is a certainty in life: Death comes to us all eventually, whether we be young or old, rich or poor."
"But what's the point of living if we're just going to die eventually? Doesn't death mean that life has no purpose?" Luster pondered.
Twilight shook her head once again. "On the contrary, it is the existence of death that gives life meaning, my student. It compels us to make the most of the time we're given in this world, to leave something behind for those that come after us. Without death, if we could truly live forever, there would be no point to life. It is because of death that we want to seek out others, to learn new things and to become better than who we were," Then she sought to reassure her troubled student. "I'm not dying anytime soon if that's what you're worried about. I intend to live a long and happy life still, as I assume you too plan to do."
"Yes, your majesty," Luster bowed her head, before she began to wonder. "But why tell me all this now if you have no plans to step down and aren't going to die?"
The alicorn simply explained as she gestured a hoof to the stained glass window displays all around her. "To prepare you for the inevitable. Good or bad, change happens. Nothing ever stays the same forever. Every generation has sought to define itself one way or another, to protect what it holds most dear. Your generation will be no different. It will fall to you and to future generations to continue the work my friends and I will leave behind when our time comes to an end."
"Does this mean I'll wield one of the Elements of Harmony like you and your friends?" The unicorn mare questioned. "Is that why you wanted me to make friends?"
"No," Twilight quickly replied to shut the idea down. "I do not anticipate you having to defend Equestria the way my friends and I did, or the way those former students from my school of friendship did. I can't predict what the future holds for you. That's for you to decide. But you must be prepared and be ready. You have a role to play in the world of Equestria, just like everyone before you. It's up to you to figure out what that role is and how you will carry it out. And whatever that role may be, I know you'll do me proud. I've seen your progress, there is very little left that I can teach you."
Luster slowly realized what her teacher was trying to tell her. "Does this mean I'm graduating from being your student?"
Twilight finally confirmed the answer as she smiled. "Yes, Luster Dawn. The circle will soon be complete. Just as I went from student to master, so too are you transitioning from student to master. It is to you and your friends that I will entrust my legacy. And it will be up to all of you to decide how best to continue that legacy, and how to make your own."
There was silence for a few moments after the alicorn finished giving her little speech. And it wasn't broken until Luster Dawn hesitantly asked. "...Is that all you wished to tell me, your majesty?"
Twilight nodded her head. "Indeed it is. So now you should depart, return to Ponyville and continue to grow and flourish in your friendship studies. I know you'll continue to make me proud."
Luster gave a salute as she raised one of her front hooves up over her forehead. "I won't let you down, Twilight! I'll ensure your legacy survives long after you're gone! You'll be an even bigger legend than Princess Celestia or Starswirl the Bearded!"
Twilight blushed ever so faintly. "I would certainly not mind such an honor, but being remembered at all is nice. Just remember what I've taught you and have tried to teach you. Make the most of the time you have. Live every day to the fullest. If you do that, I'm sure you'll be able to conquer any challenge that comes your way."
Luster smiled and hugged her mentor tightly. "I promise, Twilight! You won't be disappointed! Heck, maybe I'll take on a student of my own someday and be just like you."
"I'm sure you'll make just as fine a teacher as any other student I've known," Twilight smiled back. "Now you may return to Ponyville. I'll continue to observe your progress. And remember that you can always come to talk to me pony to pony. After all, I'm not just your teacher, I'm also your friend."
Now it was the unicorn mare's turn to blush. "Wow! All this time, I never thought about it like that. But I guess it takes a friend to know a friend... or something like that."
"Yes, something like that." Twilight chuckled.