As evening came, Thorax managed to calm himself down. Officer Scratch had excused herself and left him in the house, alone, to ponder his situation. The shaking had not stopped, but the sweating had. Did all Infiltrators deal with this? Was this part of the job?
He was interrupted by the sound of a key rustling against the door. The portal opened to reveal Octavia, dragging behind her a case, the same case he had seen her take on the train with her before. As she entered, her eyes locked on him and did not waver, even as her body turned, her head swiveled to stay trained on him.
Without breaking eye contact, she set the case down and extracted the heavy wooden cello from it, and the accompanying accessories. She straightened out the bow tie she always wore, and ran a hoof through her mane to make sure all was in order.
"What are you doing?" Thorax asked.
"What I have been doing this whole day, nay, since I've known you. Preparing."
Octavia stepped back, leaving her back to the living room's entrance. Though her eyes remained locked on Thorax's, she did sneak looks down at the bow in her hoof to make sure it was properly aligned. She tested the strings on the cello one last time, ran the bow silently along each length. Only she could hear, feel, the vibrations that came from it. All was in alignment.
"Sit down."
Thorax sat on the couch.
Octavia held up the bow, her whole body tensing up as she took her bipedal pose along the length of the instrument. She regulated her own breathing, she tuned her ears to the chirping of the night outside. She paused.
"Mister Hist. Have you heard of Carnival of the Swan?"
Thorax shook his head.
Octavia closed her eyes and the world went black. The inside of her eyelids let pass no light, not even the dim glow of the candle in the living room. The only senses she needed now were those of touch and sound, to feel the vibration in her soul and bring it forth into the world in the form that ponies could perceive. It was a dim echo of the feeling that was within her, if only those others could grasp what she did every time she picked up her cello.
Her bow began moving automatically, in time to the song she had rehearsed the whole day. Lacking an accompanying chorus to back her, she put her strength into the volume and dragged each note to fill the gap that her quartet would have normally filled.
Thorax felt himself begin to relax and drift away. In the back of his head, a thought emerged. This is a trap! Thorax ignored it. He closed his eyes as well and lay his head back on the couch. A profound sense of calm overtook him, his body sinking into the cushions and the world itself feeling distant. The thought was as nothing, and it was soon forgotten.
Octavia finished the first part of the suite and began the second verse, which was a solo for her. The suite was actually meant to be accompanied by a harp and a piano, playing her backing. In the second verse, the piano played only three notes in arpeggio, leaving the ear to her cello almost alone. The first part was a series of long and low draws, and Octavia let the sound inside her whirl into the world outside.
Thorax snapped back to reality, his throat having suddenly clenched up. The reason became obvious as his stomach began to churn, alternating between expansion and contraction. He found his lungs no longer responding to his orders to breathe, and the world grew dim. He could not even build the strength to stand, and lay in the recesses of the couch. Again, the thought emerged. A trap! Run!
Passing to the next part, Octavia's cello went half an octave higher to match the Swan's increasing pace. The second verse would end with a long, drawn out return of the harp where she held only a single note.
Thorax sat up but was unable to speak. The paralysis had come and gone without warning, and he knew not why. Octavia was playing coy, her eyes were closed and she had not noticed his struggle. Thorax reclined slightly, wondering whether or not he was in the grip of a nefarious ploy. Was it too convenient? Had Octavia been planning this, ever since she had stunned him with her clarinet a week earlier? He could only recline back into the couch in nervous anticipation.
The pain came back, seizing Thorax's legs as Octavia began the third verse. Here, in the classical description, the swan met its mate and the two began to dance. Octavia played the higher notes for the female, and the lower notes for the male, intermixing as the two fell in love and circled one another. Thorax's body wracked in agony, followed by bouts of peace, and then a return to distress. During his clear moments, he could only summon enough will to prop himself up enough not to fall over.
Now came the great finale, as the swans linked wings together and flew off into the sunset. The song narrated the story of their budding love with arpeggios rolling up and down the octaves until the swans were out of sight, and the song would end. Octavia's bow expertly brought the story to life, and, were the audience of mind to see it, cast the truth of their love in the air that the sound wore as its medium.
Thorax felt the vibrations in his skull and down to his bones. The rapid oscillations began to overpower him, and the world suddenly went completely dark as his eyes began to stop functioning entirely. His desire to scream was overcome by total paralysis in his nose and mouth. His whole body became numb, the only thing he could do was sit and helplessly wait for the feeling to end. Octavia's beautiful melody continued to roll through his ears, until, finally, he lost control of himself completely.
He cried, both in his mind and through his tear ducts.
His body began to tingle.
All through him, though he could not see it, he knew that his illusion was dropping.
With that went his balance.
Octavia finished the suite and opened her eyes, expecting to find her new lover lost in the bliss of her music.
Thorax, truly Thorax now, plunged from his perch on the couch and crashed through the coffee table.
Octavia's bow fell from her hooves, and her cello clattered against the floor a moment later.
Octavia charged forward, her body acting well before her mind was arranged enough to issue the orders. One part of her continued to exist as though nothing had happened, it continued to play back the last few seconds of her recital, being critical of it and noting down errors. Another part asked questions idly. Did Hist enjoy it? What would Vinyl have said? It was only after Octavia had pinned the black creature to the floor that her brain finally caught up, and asked the most important question.
"Where's Hist!? What did you do to him?"
"I..." the creature choked out.
Octavia brought the thing's head up from the floor and held it, suspended in midair. It was surprisingly light, and it gave no resistance now.
"Tell me! Tell me now you monster!"
"I... Hist..." it spoke again. It struggled to build the words.
Octavia brought its head crashing down with all her strength, into the floor. The changeling did not even utter a whimper of protest, it absorbed the beating with muted regret. It continued to try to gasp out a sentence.
"I - I am him..."
"No!"
Octavia put both of her forehooves on the beast's throat and squeezed with all her strength. Though the thing's wings fluttered weakly, it still did not struggle or fight. It hung listlessly as Octavia choked it.
"I will not allow it! You - you can't be - not - not..."
Octavia dropped the changeling, which landed in a heap and lay still. Octavia turned away, suddenly sick at the realizations she could no longer suppress. Though she closed her eyes, the visions in her mind's eye would not stop, and the image of Hist and this - creature - being one and the same...
Octavia opened her eyes again, to see that the world had fallen away in her absence. Gone was the carpet, the couch, her cello, the roof, the building, Ponyville, Equestria, the world. All that hung now in the infinite darkness was her, and the prone, listless form of blasphemy before her. She reached down again, and picked it up by the neck.
Its face changed. A filly's face, young, perhaps it was fifteen years old. It sneered at her, now having no trouble speaking despite the grip she had on it.
"Where's your girlfriend, dike? Vinyl off snorting coke in the bathroom?"
"Shut up!"
She tore her hoof from the creature's neck and used the freed limb to strike at the changeling's face. The creature took no notice, and resumed its sneer.
"Nopony's gonna come to your aid, you know. Who would? Just admit you're not one of us, and maybe we'll leave you alone."
"Liar! You never gave me even five minutes to myself..."
Octavia struck again at the phantom, unleashing a fresh stream of blood from its nose. Where the blood fell from its face, it trickled and dissipated into the emptiness around her. Octavia struck once more, denting the thing's muzzle at an upward angle. The face blurred and shifted again, into the face of a familiar colt.
"Woah woah, you're gonna just come up and talk to me? Just like that?"
"I thought we had something special," Octavia pleaded through her tears.
"Don't you know what a one-night stand is? I can't be seen with a fatty like you. Get lost!"
"Bastard!"
Octavia slammed the face into the floor directly beneath her, then did so again, and again. Each time she brought the beast's head back up, it was more bloodied, more battered, but still glaring at her. She brought the head down again and back up, only the face was different once more.
This face needn't say anything, it merely stared. Her mother was wise enough not to need words to say what she needed to, everything was communicated in the same stare Octavia had received all through her life. It had been her father who had talked to her, who had encouraged her, who had cared when she had come home crying. It had been her father who brought her her first instrument, and her father had been the one who taught her to play it. Mother had just stood there.
"I don't need you any more! I have friends now!" Octavia bellowed.
Her mother shut her eyes and shook her head.
"I hate you! I never want to see you again!"
Octavia threw the changeling as hard as she could into the void. She shut her eyes and held her head to her forehooves, trying to gain control of the tears that flowed like a waterfall from her. As her throat clenched, she could only barely catch her own breath between her sobbing. She forced her eyes open to see the changeling, having shifted back into the lie of Hist Amine.
"It was too easy," he said, "you didn't suspect a thing. Did you think anyone would ever love you? Did you think I would? Even a monster like me has standards. Nothing personal, you're just a means to an end."
"What - what gives you the right? How can you play with my emotions? Don't you have a heart?"
Hist grinned wickedly. "Of course not."
Octavia felt a surge run through her body, causing her fine hairs to stand on end. The void around her lit up in crimson glory, revealing her cello on the ground between her and the fallen changeling. She realized what was left to do.
The changeling began laughing as she picked the cello up by its neck. It cackled wildly as she drew the instrument up to her head, as she stood on her hind legs and arched it behind her back.
"All too easy! All too easy!" it laughed.
Octavia brought the cello down on its body with every fiber of strength she had. The changeling dropped its disguise as Hist Amine, showing its fanged, pupil-less face again. It howled in agony as the cello struck. A sickening crack echoed through the night as the wooden instrument smashed through its spine.
Now its face shifted in the face of her roommate.
"Tavi, stop!" it pleaded.
"Go to hell," Tavi growled. She hefted the cello again.
"You're going to kill him!"
The world snapped back into focus. All around her, the black fog of the void thinned, and the living room returned. Laying on the floor in front of her was Thorax, his body twisted at a grotesque angle. Over him stood Vinyl Scratch, reared on her hind legs to protect him from Octavia. With her forelegs thrown open, she stood prepared to block the next strike. It did not come. Octavia dropped the cello.
"Oh my..." Octavia whispered.
Vinyl relaxed her pose, but kept herself between Octavia and Thorax. "What happened? Is the - "
"Get out," Octavia stated.
"But - "
"Get out, Vinyl!"
Vinyl dropped to all fours, letting her gaze drift between Octavia and the cello that had clattered to the floor moments before. She shot a look at the fallen changeling, then back to Octavia. Tavi wiped her face, knocking away the tears that had pooled up.
"Fine," Vinyl said. She trotted to the still-ajar door and slammed it on her way out.
Octavia did not move from her spot, she did not check on Thorax, she did not check her cello for damage. She fell to the floor, balled up, and cried.
Before he fell unconscious, the last thing Thorax heard was sobbing coming from the pony he had thought he loved.