"Later," he murmurs the agreement, for all he cannot say what he confirms, past the storm of lightning seeped from the boy-elder's hands, the bluish indignation of qi that stirs but cannot stoke, electric.

He remembers: a long, dark alley. Five, scattered across the alleyways, glimpsed here one heartbeat, distant the next. Lan Wangji, struggling to keep pace, lacking navigational direction. He remembers, nothing explained.

Enough reveals itself now, flesh unskinned. His eyes slant, half the frown of concentration, half the strain of sight that starts to taper and dissipate at its edges. Convulsive, it will gasp and breathe and excuse itself in deeper moments of loss, later. Not yet, so. "Your strength does not self-generate."

There is an external, exhaustible reservoir that feeds Five's... ability. His condition. It does not string back to a core, unravelling in exercise, a muscle of magic drawing from the caster's resources to complete its task. It is... a stranger, distant treasury.