Flashback to them making their soul bond, there is blood mentioned in this as part of the process

                Jonghyun softly ran his fingers through Jinki’s long hair as he frowned deeply seeing the strip of white through the black locks. The last few years had proven to be hard on the prophet. The King pushing him harder and longer to produce as many visions and details of the Dark Sorcerers as he could. In doing so the white began to show in his hair near his right temple. Tonight he had arrived with the use of a thick cane he had bought a few months before when walking unassisted became difficult.

                After eating some of the bread Jonghyun had baked and drunk the tonic he made for him, Jinki had curled up on the bed using Jonghyun’s tummy as a pillow. He was facing away, but Jonghyun knew his eyes were closed, for he always did when his hair was being played with. Jonghyun lifted his gaze from the back of Jinki’s head to the book on the table across the way. He had found it when exploring the old library, back in the deep reference section. It described a powerful spell called a soul bond, one that connected two sorcerers until they were almost one. It described instances of powers being shared between the two individuals, spells power increased simply by being connected, and being such a deep connection it was painful to break.

                They had discussed marriage offhandedly, not serious enough to mean anything. Jinki had smiled so sweetly at the thought, leaning over and kissing his temple with a quick ‘Marrying you would be a dream’, before returning to his book. Jonghyun felt the truth in such a statement, but he also desired to be connected to Jinki in a deeper way. He loved him so much. Never had he felt all consumed by love for another, such a raw and passionate emotion it sometimes left him breathless. Before he lost his courage, he softly called out, “Love?”

                The quiet noise Jinki made could only be described as adorable as he to his back, shifting his head to look up at him. His eyes slowly opened, a sweet and warm smile on his face. “Hey~”

                “Are you feeling better?”

                “I am,” His hand was soft as he intertwined their fingers the best he could. “Thanks to you.”

                 “I’ve been thinking about something that I’ve been researching lately.”

                 “Oh?”

                Chewing on his bottom lip, Jonghyun’s gaze fell from Jinki’s, chest feeling a little tight in his nervousness. He met Jinki’s eyes as he asked, “Have you ever heard of a soul bond?”

                 “The memory is vague, but I believe I have.” Jinki moved his thumb on the back of Jonghyun’s hand. “It’s the connection between two sorcerers’ souls, binding them by powerful magic, right?”

                “Yes.”

                “What have you been thinking about it, exactly, Dear One?”

                 Jonghyun flashed a tiny smile, breathing out quickly, “For once I wish you’d read me again.”

                 Slowly, Jinki rose from his thigh. After letting go of his hand he swung a leg over Jonghyun’s lap, straddling him and wrapping his arms around his neck. “I don’t have to use my abilities to read what’s on your mind, Beautiful. I wish you weren’t so hesitant to open up your desires to me.”

                 “If you ended up deciding you didn’t want to be that deeply tied to me,” He rose his hand to caress his cheek softly. “I don’t know what I’d do. I love you so much Jinki. I know what the crown says about marriage and commitment of it’s sorcerers, but I-”

                “I’d leave it all for you, Dear One.” Jinki quickly cut him off, leaning forward to press a few light kisses on each corner of his lips. “You are the only good thing in my life, Jonghyun. I’d have to research what a soul bond is, more than what I know from stories my master used to tell me, but the thought of being so intertwined with you it’s as if we’re one heart,” He grins widely and it knocks the breath out of Jonghyun’s lungs. “It’s exhilarating.”

                “So you’ll think about it?”

                “Yes.” After sweetly kissing him he whispered against his lips, “I love you more than anything else, Dear One.”

------

                It was a few weeks later they stood a step away from each other, reading the other’s expression for any signs of doubt. Soon it would be midnight on the first full moon since they decided this is what they wanted. Jinki looked so bright and warm with the weeks he had hidden away from any of the King’s demands, knowing that they need him well rested if this was going to work. Behind them was the prepared cauldron. Each ingredient was already measured out in separate tiny bowls and Jonghyun’s silver ceremony knife he got as a gift from his Master at the end of his apprenticeship was laying on the dark blue velvet it was stored in usually.

                “Are you ready?” Jonghyun quietly asked.

                “We can’t reverse this, Dear one, not without a lot of pain.” Jinki caught his slightly curled hand swinging next to his side, intertwining their fingers. “To feel you as intimately as this will allow, so close… I am sure in my decision, so please don’t mistake my intention when asking if you’re sure this is what you want for second thoughts, Jonghyun.”

                “The one thing I’m entirely sure of is us.” He pushed up to kiss his lips, bumping noses as he pulled away. “I may not be a prophet, but I know we were meant to meet that day Jinki. I’m sure. I want this. I want you.”

                Jinki kept hold of Jonghyun’s hand as he led them over to the table, only letting go of it so they could add the ingredients. The old book was open on the small stand they used for the potion book Jonghyun was writing. With each different ingredient added they began to sing until finally, Jinki picked up the delicate handle of the knife. Carefully, he pressed firmly from his the bottom of his ring finger to the end of his palm on his left hand with a deep hiss. Then as he cradled his cut hand he handed the knife to Jonghyun. Once he had done the exact same the knife was discarded on the table.

                They pressed their palms together, continuing the song as they lowered their intertwined hands into the brew in the cauldron. Once the liquid had covered both of their hands, they felt it. The exhilarating rush of power and presence as the connection clicked together and solidified. Their breathing hitched just for a moment, hearts pounding rapidly as the felt the full force of the bond.

                With their hands still under the brew, they stepped around the small table until they could kiss. Jonghyun’s free hand curling tightly in Jinki’s shirt, as Jinki had his hand pulling him closer on his lower back. The kiss was messy and opened mouth. The feeling of their new bond almost addicting. All the new sensations crashing together and swirling around. All there was to them then was the other man. Nothing else mattered. When they finally pulled apart enough to speak Jinki roughly panted. “I feel so much of you.”

                “My senses are going insane. I feel so tingly all over and God,” Jonghyun had a dazed smile on his face, eyes wide as he stared at Jinki, “Do you really see the world like this? Images of the past and future keep coming and going, I- I thought I’d feel overpowered, swollen almost, with everything but..”

                “It just feels right.” Jinki laughed, light and airy as he kissed him quickly. “So right.”

                When they managed to clean and wrap each of their wounds they couldn’t find it in themselves to tidy up the rest. For they were too caught up in the way everything felt so vibrant and alive. The smallest touch, a whisper against skin, a kiss. All they could bring themselves to do was lay on the bed and explore the feeling of the other’s face against their fingers. The sensations brand new even if they knew the other’s features better than their own some days.

                Jinki hadn’t felt that renewed and centered in years, feeling the ebb and flow of their powers swirling around between the two of them. Jonghyun saw the world in such a different light. He could see little images of their lives together, memories so clear and vivid he knew them to be visions of the past. Flashes of ones that hadn’t yet occurred he knew to be possible futures for them. He opened his mouth slightly, about to let the familiar three words roll off his tongue, but as Jinki slowly smiled he knew he didn’t need to say them. For they both knew. They could feel the rush of warm, deep affection for each other.