Hindsight is 20/20
Celestia had full faith in her student Twilight. From the beginning, she had full faith in her hooves, hence why all the magic went to her. But there was something that nagged her, to everypony else Discord's betrayal was one of complete shock and surprise but to Celestia, she knew of his choice before he was even given it. She had hoped that he wouldn't fall prey to fate but he did.
She wanted to believe that what had happened wouldn't happen but she was proven wrong, oh so wrong. Everything had fallen into place as He said. It was beyond terrifying how He had known how it would all fall together. Celestia's hooves trembled a bit at each practiced, precise, and composing step. Her mask of a perfect princess was slipping as she began to grow closer to her throne room.
No pony- no creature was able to predict the future flawlessly as He had. Every prediction before had been flimsy and too far in between to be prevalent, but He spoke his foretelling as if reading a book he had read a million times. No error in his step-by-step detailed prophecy, no mistakes in his telling of the future. Celestia had tried, oh she tried to see the imperfections of His future telling but found nothing short of perfection.
He omitted places and certain periods that Tirek was slowly growing stronger in, 'to keep the game going' he'd say, but in truth, she knew it was to prove a point, to show he held the knowledge but refused to speak of it so that she couldn't enact on any information. It does not mean he let slip more information than he intended, as Celestia was a professional at wordplay, though it wasn't enough to help her little ponies.
It calmed her that he didn't hold all the pieces but it still terrified her to no end that he knew about EVERYTHING. It was startling, he had intentionally come to a point in time to her throne to tell her of the oncoming fate but had no time to truly change it.
Celestia had learned he had a silver tongue, an air of confidence when he spoke of it all, as though there was no doubt in his mind that it would all come crashing down as he foretold. Even now he may know what will occur of this meeting, and that idea alone made Celestia's fur stand at its ends. She shivered and trembled at the very prospect that all this was just a game.
She did not feel safe or secure in this battle of wits, there was only ONE creature to make her feel this way and that was when Discord got serious. But even He wasn't serious.
"Princess, He's at the throne room as you expected... we don't know how He got in but we assume it's when hysteria happened during the Tirek mess, as you requested in the letter we let him be."
Celestia inhaled slowly and steeled her nerves to speak, her jaw, however, was not as strong as her will. It shuddered and hesitated before speaking her mind.
She clenched her jaw as she caught the guard's expression shift from worry and shock.
She cleared her throat to invoke her authority, to show some kind of control of the situation as bizarre and worrisome as this. "I presume you have been monitoring him as I asked?"
He hesitated before speaking, "Y-yes"
Celestia's worries had come to her body like a tidal wave. "Has He made any unusual steps? Any strange actions?" Her voice hinted a bit of worry, her thoughts plagued with some kind of rational explanation of how He knew, some kind of demonic dealings or magical incantations.
"N-no... He's just been sitting there... looking off to one of the glass panels."
Celestia's voice was caught in her throat, no move was being made, no magic resistance to her or the Castle, just waiting to play her and her subjects like pawns.
"...when I walk in, leave this post and wait until I call you back, understand?" The guard was surprised at the serious tone shift of her voice. But he nodded and opened one of the doors to let herself in.
As the door opened light seeped through and shined onto her before immediately dimming to see the room only lit by the glass planes. Light coming from the windows with Him sitting beside one.
Celestia, try as she might, could not bring her shaking to stop as the guard closed the door, silence overtook the room before He began speaking.
"...I assume that's you, Celestia? Or maybe Luna? I do like her somewhat." He turned around to meet Celestia's eyes. His coat was gray, bland, and dreary with no expression to it, his eyes like amber yellow. He was an earth pony with no special qualities aside from having a necklace that held a green stone. He didn't even have a cutie mark to call his own.
Celestia steeled her resolve as she gained a poker face to save any emotions leaking out as a sign of weakness.
He took charge, "Good afternoon princess, I assume everything I said came to fruition?"
She hesitated before speaking, "...Good afternoon, and yes..." She had plenty of experience in keeping a conversation with an unknown ally or enemy but this was different. Her enemy had shown up at today's court with a prophecy, she took it as a strange dream and nothing more even with him warning her that it was to come true and once did, 'I will find you to see what you can offer me.'
So understandably she was beyond alien to how to go with this conversation.
"I see I'll have to start, well I require something in turn for my predictions. I think you of all ponies can understand that something as heavy as telling the future requires a heavy price. Don't you think?"
She was quick to respond. "And why should I pay for it? You knew beforehand and chose only to share with it after it was impossible to stop."
But he was not lost in keeping pace. "Ah, but how could anyone believe a stranger speaking of the collapse of the princesses? You didn't even believe me when I spoke of it in your day court."
Celestia had nothing to say.
"My services would prove invaluable so my demands are simple, I keep telling you of future threats that are more serious and I receive the royal treatment and get whatever I want when I ask."
Celestia's poker face crumbled as she showed distaste for his request. "I agree that your services would prove valuable but how can I know you will continue to see the future? And royal treatment would be grantable but you want complete control? Do you know how absurd that sounds? You would have no limits, no restrictions, and that, I, can not allow."
"Ah but you saw the proof for yourself, everything had happened as I spoke of, even if this was the only example, details of what I spoke were nothing short of perfect. I know they happened and that would be no short of precise. You know this isn't some fluke."
"I would not know, but we can discuss further options-"
"No" He spoke sharply, with a bit of spite. "This is something beyond just being an accountant or being some kind of servant to the Castle. I, in my goodwill, told you of what would happen and you spit in my face to give me less than what I am owed?" He sneered at her.
Celestia had raised her stance, spreading her wings to bring an imposing show of authority. "What you want is beyond what you are owed, nothing short of arrogance and malicious intent. You speak of doing good yet you let it all happen with little time for us to truly avoid the disaster altogether."
His frown and anger slowly morphed into a smug smile with malice glinting in his eyes.
"Then perhaps, I shall let the other side gain an advantage, hm?"
The air grew cold and sharp. Celestia's eyes narrowed. "Are you threatening me? Because if you so much as pose a threat to my ponies, I shall stop you here and now."
The earth pony lifted a hoof to his green jewel. "You speak as though you have some kind of power to stop me."
Celestia lit her horn, sparking with power. "YOU are just an earth pony, you have no magic, I've checked.
He laughed at that, "I may have no magical readings, that's true, but I can use magic like any other." He held onto his necklace with a touch of the rock, it glowed.
"What do you plan to do?"
"I give you one last chance princess, I gain whatever I want, the ultimate power to the throne and unlimited access to everything, in turn, I help you with threats that could plunge the world into darkness. Truly you think this offer is worth more than anything else, think of your 'little ponies'." He held a smug expression. "Or I could use a teleportation spell that is untraceable and use my knowledge to claim a throne of my own." He looked at her with excitement. "Does a war against a pony who can see the future sound very sound? I don't think your ponies could handle such a force."
Celestia gritted her teeth, anger swirled in her thoughts, of course, his offer was ludicrous in every sense of the word. No doubt he was playing her but a creature able to see the future? A perfect chance to protect her kingdom from anything and everything? And if she were to deny right here right now, would she be able to stop him if he could truly escape this room? Was the cost truly too great?
She lowered her wings and lowered herself to a neutral stance, what was worse was if her foes, Chrysalis, Tirek, and many more. If they were to gain access to Him, to tell the future... she had no choice.
"I-..." She had to swallow all the distaste she had for this situation. "I will... agree."
He smiled deviously, "I'm happy to hear, I didn't want to have to hurt anyone, ponies are very plush and warm."
He turned around to watch the skies through the windows. "I'm glad you saw my side before we made...an episode." Cruelly smiling he looked upon the city with lust and satisfaction.