From the source:
 
Blank Check laid on her the cot in her cell and took in all she could see in my Equestria Dreamscape. It wasn’t much. The dressed stone floor, the ceiling of similar material and wooden beams, four magical glow lamps in the corners, a simple, low wooden table with basic cushion to sit on, and the toilet. That was it.
 
Beyond was an empty void of utter darkness. Just complete black. This was the magical wards that assured that she’d stay in custody. She couldn’t even see the bars or the door of her cell. They were behind the wards to assure that she wouldn’t attempt to make them disappear. This was the arrangement that had been set up for her after she’d arrived in Canterlot. At least they’d taken that blasted blindfold off her. Except for a couple of brief moments when medical staff had examined her after her arrest the unicorn had been living in a world of complete blindness, and Blank Check had discovered that Last Thing had been true to her word.
 
Trying to remove the blindfold with her talent had been a very painful exercise in futility.  
Blank Check listened to a guard pony that walked pass her cell. Except for a couple of brief visits by medical staff she hadn’t seen a pony for several days. Her meals were teleported into her cell and the dirty dishes removed in a similar fashion. Even her interrogators had been just voices from beyond the inky darkness. Like her meals the various charges and legal documents had simply materialized on wooden table in her cell and whisked away in the same manner. She hadn’t even seen the face of the attorney who’d be assigned to her.
 
The unicorn raised her left front hoof and rubbed the inhibitor ring on her horn. It was the one courtesy her captors had extended to her. It allowed her to perform basic levitation of small objects over very short distances. At least it made eating bearable. Also her captors left her a mane comb and a curry brush so at least she could groom herself. Although she had no mirror in the cell to verify the success or failure of her efforts at maintaining appearances.
 
The ring also let her do one trick by accident. She was keeping that trick very secret because she’d knew she’d probably only get one chance to really use it.
 
She was lying on her back and staring up at ceiling when she heard a chorus of guard ponies begin chattering all at once.
 
“She’s here? Right now!” Blank Check recognized the voice as being the one who brought her lunch and dinner.
 
“Yeah she arrived a minute ago. She’s talking with the Watch Captain right now.” The unicorn was certain this voice was connected to one of the NCOs in the stockade.
 
“Why would she come down here?” The pale pink mare had never heard this voice before.
 
“Sun and moon! She’s coming this way!” Another pony chimed in.
 
Blank Check heard the quick shuffling of hooves and the clinking of armor as ponies came to attention. A few seconds there was the sound of approaching hooves, then a female voice spoke.
 
“At ease everypony. Corporal I wish to speak with the prisoner. Can you open the cell please?
 
There was muttering amongst the guard. “Uh, your Highness the prisoner can hear you through the wards, and she is very dangerous. I’d advise against entering.” One of the guard spoke up.
 
“Your concerns are appreciated Corporal. However I prefer to talk to ponies face-to-face. I will be careful. Now please open the cell door.”
 
There was a sound of fumbling keys and the squeak of the iron bar door swinging up. Then the female voice spoke again. “Thank you Corporal. Once I’ve entered please close and lock the door, and don’t be alarmed when I raise a silence bubble. I wish to speak in private with the prisoner.”
 
Then emerging through veil of darkness Princess Celestia stepped into the cell. Her great size seemed to fill the small cell. Along with her normal regalia the Co-ruler of Equestria was levitating a small wicker basket. The unicorn on the cot just glared at her.
 
“Well shit! I never imagined I’d see you showing up in my fucking cell. So your Highness. What brings you down into the fucking bowels of the stockade?”
 
Celestia body language was relaxed and she wore a smile that she’d perfected over centuries of public service. Only a slight arching of an eyebrow disturbed the perfect mask. “Why am I here you ask? I have a few questions to ask you, and I figured I’d bring you some tea in the process. The fare in the stockade is nutritious but hardly tasty.”
 
With no further ado the princess sat down and proceeded to set out a small tea spread on the low table. With this accomplished she glanced at Blank Check who had not yet left the cot. With a front hoof the princess gestured.
 
“Please dear. Come have a seat.”
 
Blank Check gave the princess a dark look, but she slowly rose off her cot and came over and sat down across from Celestia. Even sitting the pale alicorn towered over the pale pink unicorn. Once seated princess’s horn flared and Blank Check felt a silence bubble fill the cell.
 
As the prisoner looked on the Princess of the Sun levitated a carafe of tea and various condiments for it from the basket. Then a couple of saucers and tea cups floated into view. Finally a covered plate of assorted cookies floated into view.
 
With the table set the alicorn began serving tea. Blank Check watched the whole surreal thing unfold before her. The scowl never leaving her face. Finally with tea served Celestia sealed the carafe and looked at the prisoner.
 
“Now Blank Check I will cut to the chase. The case against you is rock solid. You’re looking at life in prison with likely no chance of parole. My attorney’s have gathered of enough evidence to make the charges stick with any jury in the realm.”
 
The princess proceeded to deposit a couple sugar cubes into her tea. Followed by a dollop of cream. She stirred this for a couple of seconds; then she continued her proposal.
 
“However if you willing to cooperate with the Crown I might be willing to offer you a more favorable set of terms. Several of your associates have taken up me on this offer, and they are willing to testify against you in court.”
 
“So you want me to betray my fucking Association?” The unicorn took a sip of her tea. “You know we make it a habit of killing associates who do that kind of fucking shit! Doesn’t matter if they’re in fucking prison or not.”
 
Celestia nodded her head. “True. But at the moment there isn’t enough of your Association left to swat a fly. It’s command structure has been annihilated. The majority of its members are in custody or dead. It’s known bank accounts seized, and more of its assets are being claimed by the crown every day.”
 
The alicorn leaned forward and the pleasant smile on her face melted away like a snowball on a summer day. “And the politicians, business ponies, police and other ponies that your Association had either bribed, extorted or threatened into compliance have either been arrested or are now under the protection of the Crown. Trust me Blank Check. Anypony remaining from your former Association has more immediate things to worry about than upholding some vows of vendetta!”
 
Blank Check clenched her jaw for a second then took another sip of tea. “You’re the pony who set this crackdown in motion aren’t you? The destruction of the Associations was your idea wasn’t it?
 
Celestia leaned back and glared at her. “Yes. Yes it was me. Your’s and every other Association are a cancer that I plan purge from the realm. I haven’t ruled and protected Equestria for over thousand years just to see ponies like your Association sap the strength or the faith my subjects have in the kingdom. Your days are over.”
 
Blank Check took another sip of tea as she stared up at the princess. There was a rage building in her. Anger that was guiding her next decision. She’d carefully done some tests when she was certain her captors had not been watching. It would hurt but she could do it even with the damn inhibitor ring on. She was going to teach this pretentious princess and everypony in this fucking kingdom the price they’d pay for crossing ponies like her and her associates.
 
“Well your Highness. It may be true that as an organization you’ve broken us, but the Associations are made up of individuals who have their own code of conduct that guides them even when the Association isn’t there. It can be a very powerful thing that directs our action and chooses our destiny.”
 
Celestia slowly lowered her saucer and cup back on to the table. Her eyes never left Blank Check’s “And what is this so-called code directing to do now?”
 
The mare also set her cup and saucer down and took a deep breath. “Well your Highness. It’s telling me.” Blank Check closed her eyes. “To seek vengeance”
 
Suddenly the mare’s snapped her eyes open and she looked at Celestia. Sparks shot from the inhibitor ring on her horn. Instead of their normal flint grey her eyes were glowing white orbs.
 
To be continued.

do like how the baron draws celestia. she looks so powerful and regal

You can hear the neighs and angry sipping noises.