The twins’ journey began under the cover of Mondstadt’s starry veil, their steps silent as they slipped beyond the city walls. Boreas carried a simple map etched with ley-line paths, his visions guiding them toward faint glimmers of possibility. Elowen summoned gentle winds to mask their trail—soft gusts that scattered leaves and bent grass, erasing any sign of passage.

  They traveled south, skirting familiar roads from their childhood adventures. Days blurred into nights: camping under Sumeru’s canopy, crossing Liyue’s misty mountains, always drawn toward the heart of knowledge. Their destination was the Sanctuary of Surasthana in Sumeru City—the closest point to Irminsul’s roots that mortal feet could reach without divine invitation.

  Nahida found them before they reached the Akademiya’s steps. She appeared in a quiet glade, small and serene, as though the wind itself had whispered their arrival.

  “Boreas. Elowen,” she said softly, her voice like rustling leaves. “I sensed your approach through the ley lines. You seek Irminsul’s secrets. For your father.” She had already read their minds.

  The twins exchanged glances. Boreas nodded, stepping forward. “We’ve mastered our powers, but time still claims him. Irminsul holds memories, fate—everything. If there’s a way to rewrite his mortality, to grant him immortality like Mother’s… we have to find it.”

  Nahida’s eyes held quiet sorrow. “Irminsul is not a tool for eternal life. It records, preserves, sometimes alters perception. But true immortality? That lies in realms beyond—even gods erode over time.”

  Elowen clenched her fists, a faint breeze stirring the air. “Then show us. Let us explore its branches. We’ve come this far.”

  Nahida hesitated, then extended a hand. “Very well. But remember: knowledge from Irminsul comes at a cost. It may change more than you intend.”

  She led them into the depths of the Akademiya, past hidden wards and ancient seals, to a chamber where the air hummed with latent energy. A small Irminsul sprout—connected to the greater tree—glowed faintly in the center. Nahida placed her palms against it, and the world shifted.

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  They fell into the tree’s embrace—not physically, but in spirit. Visions cascaded like waterfalls of light: Teyvat’s history unfolding in threads of memory. Boreas navigated the streams, seeking whispers of immortality. He glimpsed adepti contracts binding souls to eternal vigil; the erosion that plagued even Archons; forbidden knowledge from the Abyss that twisted life into unending torment.

  Deeper still, they found fragments—secrets buried in Irminsul’s roots.

  One thread revealed the Seelies: ancient beings who achieved a form of immortality through love, though cursed to fade. Another spoke of Khaenri’ah’s machines, eternal constructs that mimicked life without end. But true, unburdened immortality? It eluded them, tangled in warnings of “imbalance” and “celestial retribution.”

  Elowen shaped winds to probe further, parting veils of forgotten lore. They uncovered a faint echo: Irminsul could rewrite fate, extending lifespans by altering records of “erosion”—the slow decay that afflicted immortals. For mortals, it might bind a soul to the ley lines, drawing eternal sustenance like the tree itself. But the cost… memories lost, identities shifted, the risk of becoming something no longer human.

  As they delved, a vision struck Boreas: their father, ageless but hollow, eyes empty of the warmth they knew. “This could break him,” he whispered.

  Elowen pulled back, winds faltering. “Or save him. We have to try.”

  Nahida’s voice echoed in the haze. “Choose wisely. Irminsul does not grant— it reshapes.”

  They emerged gasping, the chamber’s glow fading. Hours had passed like minutes. Nahida regarded them sadly.

  “You’ve seen the secrets,” she said. “Immortality through Irminsul is no gift. It is a rewrite. Your father may live forever, but would he still be him?”

  The twins shared a determined look. Boreas folded the map. “We need more. The Abyss… Khaenri’ah… we’ll find a way that doesn’t steal his soul.”

  Elowen nodded. “For family.”

  As they departed Sumeru under gathering clouds, Nahida watched them go. “May the winds guide you,” she murmured. “And may you find what you truly seek—not endless days, but cherished ones.”

  The journey continued. Irminsul’s whispers lingered in their minds—promises of eternity, shadowed by sacrifice.

  But the twins pressed on, hearts fixed on a future where time could not part them from their father.