"So...this is how we say goodbye."
Twilight's sadness was there on her face for all to see, and she walked slowly to the devastating sight before her. The Tree of Harmony, once so great and magnificent, now nothing but a shattered ruin before her. The Elements, gone, their power vanished from this world forever. And while victory against the darkness of king Sombra had indeed been accomplished, there was no escaping the bitter feeling that she'd still failed. As she approached, she took a single crystalline fragment of the Tree that was, holding it in her hoof as she sighed.
"I'm sorry. I wish I could have done more to save you."
She knew the Tree couldn't hear her, but she needed to say it all the same. The piece fell from her hoof, and her head hung with shame over her belief that she had failed. But in this time, alone in this place, a new feeling came to her. It was a coldness in the air, and a chill down her spine. She didn't think much of it at first, yet as the moments passed, she began to feel as though this sensation were familiar to her somehow. Soon, her eyes widened, doubly so as a voice spoke softly behind her.
"So, it is as I sensed. The Tree is gone."
Twilight spun in place, looking on as she saw the one whom she'd suspected was there. Stygian, better known as the Pony of Shadows, towering above her and looking down with that face that was so hard to read. Twilight's wings flared up, and she readied herself for a fight, but the ancient being of Equestrian legend made no move against her.
"Peace, Princess. I do not come here for battle."
Twilight didn't know how to feel. This was a figure who had plagued the stories of pony children for generations, yet her last encounter informed her well that this was not the slathering monster of the fables, but something entirely different. But she did not cease her wariness, and narrowed her eyes towards this new arrival.
"Stygian. Why are you here?"
The enormous and dark figure walked past her, with Twilight keeping her eyes on him at all times, and she watched as he too approached the broken remains of the tree. A silence fell between them and Stygian merely looked down to it for a time. Finally though, he spoke.
"I came to pay my respects. This power has, since ages past, been my equal. My opposite. It has always been the two of us through these long millennia. Yet now...
He sighed.
"...now it is only I."
Twilight felt herself calm down, but only by a little, and she furled her wings again before walking alongside him. Sadness returned to her, and she drooped her ears.
"It was my fault. I was so confident the Elements had beaten him. Too confident. And then...and then..."
She didn't finish, instead looking away from the Tree's remains in shame. Stygian did not look to her, yet spoke all the same.
"Darkness has always been sly and cunning, Princess. Take it from one who knows it best."
Another silence, but it did not last long, for Twilight soon heard a sound she was not expecting to hear. It was laughter, and one that caused her to look to her unexpected companion.
"You think this is funny?!"
Stygian, whose laugh was fairly dry to hear, slowly shook his head.
"Not exactly. I simply recall an odd thought of mine from long ago. Which of the two of us would fade from this world first? I'll be honest...I never expected it to be the Tree."
His brow furrowed.
"Seems everything is changing these days."
Twilight had no idea what to think right now. This was, after all, the avatar, the embodiment of all darkness and evil in their world. Yet here he was, almost mourning the thing that embodied all of the opposite. Light, goodness, friendship, that was the Tree, yet Stygian seemed to miss it as much as she did. Regardless, her attention was drawn again to the fact that he was moving, giving her a quick nod before staring to walk towards the cave entrance. And here, for whatever reason, she felt compelled to speak out.
"Wait!"
Stygian halted, turning back to look at her. He said nothing, instead waiting for her to speak first, and while she hesitated to do so, words did eventually come from her.
"The tree is gone...and so are the Elements. Our chief weapon in the fight against evil is taken from us, and I don't know if there will ever be something we can find that can replace it."
She took a single step forward.
"You're powerful, Stygian. Powerful enough to be the Tree's rival. I was wondering..."
The Princess faltered, but only for a moment.
"...could you be an aid to us? Like the Tree was?"
To say that Stygian was taken aback was an understatement, as he looked utterly astonished at such words, to the point of being speechless. But after almost an entire minute of saying nothing, the ancient darkness finally responded.
"Princess...you ask me to be your ally in the Tree's place?"
Slowly, Twilight nodded, and Stygian was left with this uncertainty that, perhaps, he'd never felt before in his life. Twilight nervously awaited his answer, but instead, what she got was another dry chortle.
"Oh my...I honestly never thought I'd get to know what that felt like," Stygian remarked.
Twilight frowned slightly.
"What what felt like?"
The spirit glanced back to her, his expression softening.
"...Being wanted."
Twilight's ears drooped again, and for just a moment, she remembered the isolation that this being had endured its whole existence. Shunned, feared, locked away because of how ponies perceived him. And now, in this place, having somepony come up to him and let him know that he was actually needed. It must have been the most foreign experience in the world for him. She wondered if that alone would compel him to accept her offer. Yet, as she heard him sigh, she knew in her heart that this would not be.
"I thank you for that feeling, Princess...but I cannot stand by your side."
The young alicorn hung her head slightly.
"I see. So...darkness has outweighed light after all."
But here, Stygian shook his head.
"No...it will not."
Twilight looked back to him, confused, and listening well as he explained.
"The Tree and I...I said before we are two sides of the same coin. But we are also of an age. An ancient age. An age that, while certainly casting a large shadow on the time you live in, may well have outlived its place in this world."
He again turned from her, taking a step towards the entrance.
"If this world no longer has the Tree...then perhaps my time has come as well."
Naturally, Twilight was shocked to hear that.
"What?! Wha...what are you talking about?!"
Another long sigh from Stygian.
"Twilight...darkness I may be, but I have never sought to disrupt the balance of this world. If Harmony has faded...so too must I."
Unbeknownst to her, the ancient force smirked slightly.
"Though know that neither of us may be as gone as we appear to be. There may be some things yet that surprise you."
But Twilight was still not handling this well.
"All these things...learning I'll be ruling Equestria...losing the Tree...I just don't know what I'm going to do."
Stygian did not look to her, at least at first. But after a time, he gradually cast a glance to her.
"Oh, Twilight...the past generations really did spoil things for you youths, didn't it?"
Twilight looked up to him as he explained.
"Discord, Tirek, myself, all problems those of the past failed to deal with. Ancient shadows that plagued your generation. Inheriting the past's problems should not have been what you and your friends were made to do in your lives."
Twilight understood his words, and perhaps on some level she agreed with them. Yet as she looked back to that life, she couldn't help but smile.
"Maybe...but I wouldn't have traded my time for anything."
A small smile crept onto Stygian's shadowy lips.
"Then perhaps you are indeed the wisest alicorn of all."
He again looked away, walking towards the cave entrance, but as he did so, Twilight trotted a few steps closer to him.
"There'll be something else, won't there? Some other evil we'll have to fight?"
Stygian, having finally reached the entrance, chuckled.
"Oh, my dear child, there will always be evil to fight. Darkness did not end when your mentor and her sister vanquished Sombra and Discord in their day. It did not pass when you and your friends defeated Tirek and the Storm king. And it will not pass when the next generation has their turn to fight it."
He looked back to her.
"Darkness and light. Peace and conflict. Harmony and strife. A cycle of one leading into the other. Such it has always been, and such it will always be."
Twilight was understandably upset by that notion. That no matter how hard she and her friends fought, some evil would always be out there, ready to hurt and dominate after the passing of years. Stygian recognised this in her, and so, in a moment few would expect from the avatar of darkness, decided to show some kindness in his final moment in this world.
"But perhaps...that is simply the cynicism of an old stallion."
Twilight looked up to him, just in time to see a smile on his face.
"Take heart, Princess Twilight Sparkle...for you and yours may well strike evil from this world forever. And if so...I wish you luck in the world you usher in with its fall."
Twilight was stunned, but she nevertheless smiled back, giving a small bow of her head. Stygian bowed back, then looked up, to the shining sun in the sky, and took a final deep breath. Twilight watched, astounded, as he began to fade away, like a mist being blown by an especially strong wind. Where once there was an imposing stallion of shadow, now he was diminishing, growing smaller and smaller until he was naught by a wisp of smoke, and that too passed on in the moment that followed. So, he was gone, perhaps forever from this world, and had left her all alone in this place. She didn't know what she and her friends would do, but having seen and heard what she had, she knew at least what she needed to say.
"Farewell, Stygian, Lord of Shadows...and thank you."