This is a Jack x Aku ficlet based on a scene from The Ancient Magus Bride, episode 9, so minor spoilers for that. Also, the backstory for this scene is mainly based on the plot from the anime, but I haven't figured a lot of it out. This is just a taster of what it could be like if Chise and Elias were replaced with Jack and Aku.
Not NSFW, but vaguely suggestive content ahead.
If the pairing triggers you, just don't read it.
Those Who Will Not Hear
He'd been told not to go into that room – the one where the demon resided. But Jack wasn't afraid.
He'd encountered Aku many times in his life, and had grown very used to the demon's habits, some of them terrifying, some irritating, some even drawing a little sympathy from him. The lair had been far too quiet for his liking, and despite Aku's hold over him, and no matter how much he tried to intimidate him by showing his ownership over the samurai, Jack would not let it affect him.
Earlier on, when he'd been attacked, he had never seen Aku react in such a way – not once. It was as if… he had defended him? Turning into such a huge form and taking a multitude of blows in his place. He knew he must be going mad if he could think the demon was capable of compassion, especially since they were supposed to be enemies. Aku didn't care for anyone. He was self-obsessed, tyrannical, and enjoyed the suffering of others.
And yet, during his time being trapped in this place, Jack had noticed a change within the lord of darkness. He was not as aggressive as he used to be, and even went as far as seeking Jack out for counselling when it suited him. He would even advise him not to venture outside for safety reasons. Was this a tiny glimmer of kindness? Or, at least, a protective instinct? Anyone would say the thought was ridiculous, but he couldn't shake it. Something was definitely strange about him.
Jack could feel the wound in his hip still throbbing, despite the strong bandage one of the servants had applied. He was concerned by Aku's uncharacteristic absence, and his curiosity beckoned him to the room where the demon hid. Despite the warnings not to, Jack was brave, as he knew Aku so well, so knocked on the door without a second thought.
"Aku? Is something wrong?"
No reply. Just an eerie silence.
Perhaps it would be safe to open the door, just to check everything was in order. He didn't want the demon sneaking off after all.
Slowly, carefully, he pressed down on the handle, pushing the enormous door open. He was greeted only by darkness as he stood in the doorway, and not even the bright flames of Aku's eyes could be spotted. It was if the room was empty.
"Where are you?" Jack demanded. "If you're hiding away like a coward, I'll have no choice but to-"
His words were cut short by an almighty rush of air as something pinned him against the wall, shocking him to the core. It was not a distinguishable body, but a huge, ink-like mass that only Aku could possess. Something was wrong about him, however. His form was spreading all over the room, like a spillage he couldn't control, and Jack could see a fear in the eyes above him. He seemed… weak. His form was heaving to and fro as he panted in exhaustion.
"You… should not be here, samurai," Aku growled breathlessly. "You're not permitted to see me like this."
"Why not?" Jack asked calmly. "I know exactly what you're like, and you choose to conceal yourself without a word. I have a right to see you."
The samurai took a moment to examine Aku's form more carefully, realising how disintegrated it looked. His black essence was torn at the corners, he was slightly off-balance, and his claws were trembling as they pressed against the wall either side of Jack.
"I can't control my body," he murmured, in an odd moment of weakness, "Nothing I do will restrain it. You're such a fool to come here – if you stay, you have no idea what I could do."
Jack wasn't sure if it was a threat, or a protective warning. Something in the demon's voice told him it was the latter. He could see how frail he was, and how frightened he seemed, of himself. Jack, not for the first time, felt a degree of pity.
"You can't make me leave. I shall stay for as long as I see fit. You cannot expect to stay like this alone, can you?"
Aku stared in disbelief, and even more so when Jack held out his hands in an inviting gesture. "Here. Let me see you."
After some hesitation, Aku did as he was bid, and the feeling of their hands together was one of the oddest sensations either of them had experienced. All through the evening, Jack sat with him, let him know he had company, all while Aku tried to let his body settle. Sometimes, Jack let his hands wander to the demon's waist, as an act of reassurance, and he thought about how alien this would have seemed only months ago. Why was he touching him like this? Why would ever will himself to be here… like this?
It wasn't long until the samurai felt himself tiring, unwillingly falling asleep in Aku's makeshift bed. He was briefly aware, during the midst of sleep, of sharp fingers running through his loose hair, rather forcefully, making his head hurt. He may have been dreaming, but he was sure he felt another hand touching his waist at the same time, warm breath tickling his left ear… and had there been something soft and gentle, like a tongue, gracing his cheek too?
Hours later, he did not remember if it was reality or a dream. He suddenly sat up from sleep, seeing the sunlight now flowing into the room, dizzy with lack of memory. When he looked around for Aku, he found himself disappointed.
For he was long gone.