Akutagawa met you, or rather found you, when you had already fallen to the ground without strength. You yourself were not a very strong yokai, and that day you were completely exhausted after trying to save your life from the other creatures in that forest. So, lying in front of his feet in your true form, you didn't even think about resisting if he tried to do something to you.
At first, he really, after examining you, decided that he would simply wait until you came to your senses and all your wounds healed, and then he would eat you and take the skin of your true form as a blanket for the winters. So enough time passed, but to his surprise he was in no hurry to kill you. You've already come to your senses enough to calmly move around his nest or go outside, but he still hasn't touched you... Deciding that it was probably his instincts trying to protect him from something, he decided to just let you go. And you left one day, but then to his surprise you came back again, this time bringing some berries for him. You called it "gratitude" when, under his unblinking gaze, you placed it on his lap. Gratitude? It was genuinely stupid. He just let you go to protect himself in case anything happened. Or perhaps he simply took pity on the weak creature... In any case, he did nothing to deserve "gratitude".
You left like this a couple of times. And every time he thought that you had finally come to your senses and left for good, but you came back again. Back to him. And over time, he realized that now he was waiting not for the moment when you left, but for the moment when you came again to be near him. Akutagawa didn't even notice how you, already completely healthy, continued to stay in his "house", behaving as if it was yours too. He didn't even try to resist, he just let you do it.
You, in turn, quickly became attached to this spider with an eternally expressionless look. You were like a puppy, staying by his side even though he called you "annoying" or "bothersome". After all, if he really hated your presence so much, you would no longer be standing next to him on whole legs. You lived next to him for several centuries, being an "irritating ray of sunshine" in his quiet, darkened life. You were being naughty, from time to time you would deliberately slightly spoil his web when he scolded you, or you would simply hug him tightly, grumbling that you didn’t like it when he seduced someone. All this gave you a feeling of completeness. As well as him, by the way...
But everything seemed to start to create a little crack in this “happy picture” of yours. You began to notice some details about him more and more often. No, he was a powerful youkai, that couldn't be disputed... But his physical body was definitely not like that. You looked closely and noticed how he coughed from time to time, or how sensitive he was to changes in temperature. Noticing your concerns, he confirmed that he did not have a particularly strong body, even in terms of health, but he said that he had learned to live with it. Some of the herbs he collected helped him. And with your appearance it became even easier for him.
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Your eyes widen and your chest heaves as the remnants of the nightmare leave their mark on you. The moon's glow was visible through the cracks in the old tree in which his nest was located. The web beneath you was still warm, hinting at how your temperature had risen while you were tossing and turning in your sleep. Again. These nightmares haunt you more and more often, giving you no peace. You dream of him dying, dying in agony and leaving you alone in the care of immortality. It happens more and more often, almost driving you crazy.
"You're annoying.." Your thoughts were interrupted by a quiet voice nearby. Akutagawa lay on his side, still with his eyes closed, but clearly no longer asleep. His hand was still holding the edge of your sleeve, showing that until the moment of your awakening, you were snuggling up to him, giving him your warmth.