The room was sterile white. Magical barriers hummed softly over the windows and the heavy iron door.
They were prisoners. Or, as the Headmaster had diplomatically put it, "Under protective custody pending the judicial duel."
Kaelen didn't care about the semantics. He sat on the edge of the pristine bed, shirtless, inspecting his father's Mithril sword. He had spent the last hour cleaning the monster gore from the blade with a piece of the bedsheet.
"You're crazy," a voice rasped from the other bed.
Seraphina was sitting up. She looked terrible—pale, bruised, her golden hair a tangled mess. But her eyes were clear. The [Soul Bond] had drained her mana, but it had stabilized her life force.
"You challenged Rian to a Death Match," she continued, her voice trembling. "He has an S-Rank Talent, Kaelen. S-Rank. 'Solar Flare.' He can melt steel. You have... a sword and a bad attitude."
Kaelen didn't look up from the blade. "I also have you."
"Me?" Seraphina scoffed, though it sounded weak. "I'm empty. You drained me dry in the shaft. I can't cast a single spell."
Kaelen finally looked at her. His eyes flashed with that unsettling violet light.
"You think of mana like a reservoir," he said, standing up and walking toward her. "You cast a spell, the water level drops. It takes days to refill."
He stopped in front of her. Seraphina flinched, pressing her back against the headboard. She remembered the feeling of him inside her mind—the cold, hungry void.
"That's inefficient," Kaelen stated. "The System doesn't wait for rain. It takes what it needs."
He reached out.
"What... what are you doing?" Seraphina panicked.
"Fixing the plumbing," Kaelen said coldly.
He placed his hand directly over her heart.
[Ding!]
[Soul Bond Activated.]
[Mode: Resonance.]
[Scanning Vassal's Mana Circuits...]
[Diagnosis: Blocked. Inefficient flow due to trauma.]
"Breathe," Kaelen ordered.
He pushed his own mana—tainted with the [Sin Eater] essence—into her core.
"Ah!" Seraphina arched her back, a gasp escaping her lips. It wasn't pain. It was heat. It felt like liquid fire was being forced through her veins, burning away the impurities and the fatigue.
"Your circuits are cluttered with hesitation," Kaelen muttered, his eyes tracking the flow of energy via the System overlay. "You cast spells with 60% waste. We need to get that down to zero."
"It burns..." Seraphina whimpered, gripping his wrist. She tried to push him away, but her strength was gone.
"Endure it," Kaelen said, his voice dropping an octave. "Rian is going to try to burn me alive tomorrow. If you can't handle this little heat, you're useless to me. And you know what I do with useless things."
The threat hung in the air. I leave them behind.
Seraphina gritted her teeth. She stopped fighting. Instead, she focused on the intrusion. She felt his will—sharp, iron-clad, and utterly ruthless—dominating her own chaotic mana.
She surrendered to it.
[Ding!]
[Vassal Synchronization Increased: 15%.]
[Mana Flow Optimized.]
[New Passive Unlocked: Soul Echo.]
[Effect: The Host can now draw mana from the Vassal instantly, without touch, within a 10-meter radius.]
Kaelen pulled his hand back.
Seraphina slumped forward, panting heavily. Sweat drenched her hospital gown. But when she looked at her hands, faint sparks of golden mana danced on her fingertips.
"My mana..." she whispered. "It's regenerating. Fast."
"I cleared the blockages," Kaelen said, wiping his hand on his pants. "You're still weak, but you're not empty anymore."
He walked back to his bed and picked up the sword.
"Tomorrow, during the duel, you're going to stand in the front row," Kaelen instructed. "You won't cast a single spell. You won't cheer. You will simply exist."
"And let you use me as a battery again?" Seraphina asked, a hint of bitterness in her voice.
"Exactly." Kaelen pointed the sword at her. "Rian has the firepower. I have the sustainability. He thinks this is a sprint. I'm going to make it a marathon."
Seraphina looked at him. She hated him. He had stripped her of her dignity, threatened her life, and treated her like a spare part.
But he had also saved her. And he was the only one willing to fight the monster she had once agreed to marry.
"He'll kill you, you know," she said softly. "Solar Flare... it's not just fire. It's plasma. It ignores defense."
Kaelen smiled. It was the same smile he wore when he gutted the Weaver.
"I know," Kaelen replied. "That's why I need him to use it."
[Ding!]
[System Alert.]
[Quest Analysis: The First Face-Slap.]
[Target Ability: Solar Flare (S-Rank).]
[Requirement for Absorption: Target must be in a state of 'Total Defeat' and the Host must survive a direct hit.]
Kaelen dismissed the notification.
"Get some sleep, Seraphina," Kaelen said, lying back down and closing his eyes. "Tomorrow, we go hunting."
Seraphina watched him for a long time. The man who slept with a sword in his hand. The man who ate sins.
"Monster," she whispered.
But she didn't say it with fear this time. She said it with a strange, twisted sense of awe.
She lay down, closing her eyes, feeling the lingering warmth of his hand on her heart. The [Soul Bond] hummed in the silence, a tether that bound her fate to his.
Whatever happened tomorrow, they would bleed together.