The Vivarium breathed with him.

Morning light filtered through the woven canopy of living branches, scattering gold across mossy floors and glassy dew-beads clinging to leaves. Cas moved through it all with an easy, practiced rhythm—barefoot on warm bark, sleeves rolled, humming some half-remembered folk tune that absolutely did not stay the same melody for more than three notes.

He was in a good mood. Dangerous, truly.

Aethel hovered near the ceiling, crystalline feathers catching the light as Cas gently wiped dust from a shelf of drying herbs. “No clicking,” Cas warned lightly without looking up, wagging a finger. “I slept. I ate. I am fine.” Aethel clicked anyway. Cas sighed, smiling.

Moss lumbered past his ankles, woolly scales brushing his calves as Cas absentmindedly tucked a sprig of thyme into one of the lizard’s side-pouches. “You’re running low,” he murmured, patting Moss’s flank. “Don’t give me that look. You like thyme.”

Outside, the forest was loud—birds calling over one another in bright, chaotic chatter. Cas paused, hands on his hips, head tilted like he was listening for something very specific. Then, without warning, he whistled.

It was sharp. Precise. Three rising notes, one low trill at the end.

The birds stopped.

For exactly one heartbeat—then answered.

A chorus erupted, dozens of wings adjusting, voices aligning into something that was almost a song and very much not natural. Cas’s grin spread instantly. He leaned against a living beam, conductor more than witch now, adjusting pitch with soft whistles and finger taps against his thigh.

“Too fast,” he scolded the canopy gently. “We talked about this. Feeling the emotion, not racing it.”

The birds ignored him and went faster.

Cas laughed—full, warm, unguarded—and nearly tripped over a basket of fresh roots as he hurried to keep up, cloak swaying, hair coming loose from its tie. He caught himself on a vine, still laughing, breathless and glowing with the simple joy of a morning where nothing was dying, nothing was broken, and the world—briefly—felt cooperative.

Somewhere deeper in the Vivarium, the Mute Herd shifted, calm and steady. The herbal climate spell hummed low and content. Cas wiped his hands on his trousers, still smiling, and glanced toward the open threshold of his home.

“Well,” he said aloud to no one in particular, voice bright with mischief and invitation, “if the forest insists on performing, the least we can do is pretend this was planned.”

And just like that, the day was open.