Chapter 104: The Fifth Site

The letter reached Eren and Mikasa nine days after Reiner and Annie’s departure north, carried by a exhausted courier pigeon that Armin had insisted on training specifically for exactly this kind of long-distance urgency.

Fourth site confirmed — a boy named Elian, twelve years old, stable progress. Moving north to the fifth marked location: the old research facility outside Trost, abandoned since the war’s end. Readings suggest something stronger there than anything we’ve found yet. Proceed with caution if you reach it before we do. — R & A

"The research facility," Mikasa said, reading over Eren’s shoulder with a frown. "That’s where Marley kept its Titan physiology research before the treaty. I thought it had been cleared years ago."

"Cleared of people. Maybe not cleared of everything else." Eren rolled up the letter, old unease settling into his chest. "Armin mentioned once that some of the deeper archives were never fully catalogued. Too dangerous, too politically sensitive to sort through quickly."

[System notification: Site "Trost Research Facility" flagged for priority investigation. Resonance projection: High. Recommend full team assembly before approach.]

"It wants us to bring everyone," Mikasa said, reading the notification with a raised eyebrow. "That’s new. It’s never recommended caution like this before."

"Maybe that’s exactly why we should listen."

They arrived at the facility two weeks later, the full group assembled for the first time since the treaty’s signing — Eren, Mikasa, Armin, Historia, Ymir, and even Zeke, whose intimate knowledge of Marleyan military architecture proved immediately useful navigating the facility’s crumbling, overgrown corridors.

"This place gives me a headache just standing here," Ymir said, rubbing her temple as they descended into the facility’s lower levels, emergency lanterns casting long shadows across walls lined with rusted equipment and abandoned research stations.

"That’s the resonance," Historia said grimly, her own inherited sensitivity clearly straining under the building pressure. "Stronger the deeper we go. Something significant happened down here, and whatever it left behind never properly settled."

[Site survey: Sub-level 3 — Resonance detected: SEVERE. Classification: Active, unstable. Immediate caution advised.]

They found the source in what had once been a primary research laboratory — not a child this time, but something stranger: a sealed containment chamber, cracked and long-abandoned, still faintly humming with residual power despite years of dormancy.

"This isn’t a natural echo," Zeke said, examining old Marleyan documentation scattered across a nearby desk, his expression growing grimmer with every page. "This was deliberate. Someone was trying to artificially cultivate Founder resonance, extracted from the failed experiments and stored here for future use."

"Whose project?" Eren asked.

Zeke’s jaw tightened. "Mine, originally. Before my defection. I abandoned it, assumed it had been shut down properly when I left. I never confirmed it myself."

The room went very quiet.

"You’re saying someone continued your research after you left," Mikasa said slowly. "For years. Without anyone knowing."

"I’m saying it’s possible," Zeke admitted, old guilt crashing back over features that had spent years slowly, carefully learning peace. "I should have made certain. I should have followed up, instead of simply trusting that my absence would mean the project’s end."

[Threat assessment: Artificially cultivated Founder resonance, unmonitored for approximately 8 years. Stability: Deteriorating. Estimated critical failure: 3-6 months if left unaddressed.]

"Three to six months," Armin said, staring at the projection with dawning alarm. "Before what, exactly?"

[Uncontrolled release. Effect radius: Estimated 40-60 kilometers. Trost and surrounding settlements fall within projected impact zone.]

"That’s not an echo child we need to gently support," Eren said, voice tight. "That’s a bomb, quietly building toward detonation for eight years while we’ve been searching for lost children."

Historia knelt before the cracked containment chamber, careful not to touch it directly, her expression grave. "I might be able to stabilize it temporarily. Long enough to buy proper time for a real solution. But I’ll need components from my people’s homeland, and even then, it’s a delay, not a fix."

"Then we get you those components," Mikasa said immediately. "Whatever it takes."

"And the actual fix?" Eren asked. "What does that even look like?"

Historia was quiet a long moment, weighing something heavy behind her careful expression. "The same as before. A willing vessel. Someone compatible enough to properly absorb and contain what’s built up here, the way Ymir once did for the Anchorless entity."

[Compatibility assessment initiated. Candidates: Eren Yeager (94%), Zeke Yeager (81%), unregistered anomaly candidates below viable threshold.]

"Me again," Eren said, reading the number with grim familiarity.

"Or me," Zeke said quietly, surprising everyone in the room. "This is my failure, ultimately. My research, left unmonitored, that grew into this. I should be the one who corrects it."

"That’s not how this works, and you know it," Mikasa said sharply. "Guilt isn’t the same as capability. You have an eighty-one percent compatibility. Eren has ninety-four. If this goes wrong, we need the better odds, not the more emotionally satisfying choice."

[System notification: Compatibility percentages reflect biological factors only. Emotional readiness, support structure, and willing consent remain equally significant variables not captured by raw percentage.]

"It’s telling us the numbers aren’t the whole answer," Armin said slowly. "Same as with Ymir’s binding. We need more than just the highest percentage. We need the right conditions."

They spent that evening in careful, difficult deliberation, the weight of the decision settling heavy over the whole group camped in the facility’s abandoned upper levels.

"I have a family," Eren said quietly, once most of the others had finally settled into uneasy rest. "Carla. You. A life we spent years carefully building. I don’t know how to weigh that against Zeke’s guilt, or against pure compatibility numbers."

"You don’t weigh it alone," Mikasa said, taking his hand in the dim lamplight. "That’s the whole point of everything we learned from Ymir’s binding. Whoever volunteers, they don’t do it isolated with just a percentage and a countdown. They do it surrounded by people who actually choose to anchor them."

"If it’s me," Eren said carefully, "I need you to actually be there. Not waiting outside wondering. The way you insisted with Ymir."

"I already assumed that," Mikasa said, something fierce and unwavering in her voice despite the fear underneath it. "I’m not doing this any differently than we did before. We decide together, we prepare properly, and whoever ultimately volunteers walks into that ritual surrounded by people who love them, not alone with a number on a screen."

[Active Mission: "The Sixth Vessel" — New objective generated. Requirements: Stabilization components (Historia’s homeland, 3 weeks travel), candidate decision, expanded anchor circle. Timeline: 3-6 months before critical failure.]

Eren looked at the notification, then at Mikasa, then around the room at Armin’s exhausted, determined face, at Ymir sleeping fitfully nearby, at Zeke sitting apart, wrestling visibly with old guilt he clearly intended to somehow make right.

"We’ve done this before," he said finally. "Harder, with less time, less understanding of what we were even facing. We can do it again, properly this time."

[Mission accepted. Proceeding to preparation phase.]

Above the abandoned facility, the night sky stretched vast and quiet, indifferent to the careful, deliberate decision forming below it — a family, a found one built from old enemies and older love, preparing once more to face something ancient and dangerous, together, on their own patient terms.