The thing about building a sky is that you cannot build it the way you imagine.
Ethan had spent his first week mostly observing. The Substrate was alive in the most fundamental sense — buzzing with chemistry and the slow, enormous logic of evolutionary pressure. But the sky concerned him.
Abel's atmosphere scattered light at a frequency that would produce a yellow-green sky at noon, transitioning to deep red at the horizon. It wasn't a problem. Life would adapt. It always did. But Ethan found, sitting at his table at three in the morning with the Engine warm in his hands, that he cared. He cared about the color of that sky in a way that surprised him, given that no creature in that world yet had eyes to see it.
He spent two days running calculations. Then he made his first intervention. A 2.3% adjustment to the atmospheric scattering coefficient. The kind of change that would, over millions of years of Substrate time, result in a sky shading from deep violet at zenith to amber at the horizon.
The cost was a headache that lasted six hours and a nosebleed that stopped after ten minutes.
Small price, he wrote. Note: even minor interventions have physical cost. Track carefully.
He had called Maya on day four. Dr. Maya Osei, cosmologist, the closest thing Ethan had to a friend and the only person in his field whose intelligence he had never felt the need to perform for.
"You need company," Maya said. "I'll come over."
"I don't need company. I called to tell you I'm okay."
"People who are okay don't call to announce it at eleven PM."
She came over the following Saturday. Near the end of the evening, Maya pointed at the Engine.
"What's that?"
"Something my grandfather left me."
Maya studied it from across the table without approaching it. As if some part of her understood she should ask permission.
"Can I see it?"
"Not yet."
She looked at him. "I'll tell you about it eventually," he said. "I'm still figuring it out myself."
Maya nodded. She didn't press. This was one of the things Ethan valued most about her — she was curious without being compulsive about it.
After she left, Ethan sat with the Engine until two in the morning. In the Substrate, one lineage of microbial organisms was behaving in a way that deviated from standard behavior. They were clustering — not passively, but with a complexity that suggested coordination. Individual cells at the periphery were sacrificing themselves, releasing chemical signals, feeding the interior cells.
He watched for three hours. The clusters grew. Some split. Some failed. A few, along the coastlines of the middle continent, held.
He did not intervene. He had already decided on a principle: Observe first. The world knows what it wants to become better than I do. My job is to provide conditions, not outcomes. Outcomes belong to them.
The sky in the Substrate, at the terminator line between day and night, was turning violet. It was beautiful. No one in that world could see it yet. He watched anyway.