Ethan realized the twelve percent wasn't vanishing—it was being *taken*.
He'd mapped the energy flows for three weeks now, watching how stellar radiation transformed into heat, motion, chemical bonds. The missing fraction never varied. Twelve percent of every joule, every electron-volt, every quantum of action disappeared between cause and effect like a tithe to an invisible church.
But tonight, tracking a volcanic eruption on the southern continent, he caught something new.
The magma chamber's pressure had been building for months. When it finally breached the surface, the explosion should have released energy equivalent to a small nuclear weapon—all of it traceable through the shockwave, the thermal bloom, the mass of ejected rock.
Twelve percent vanished as expected.
But for exactly 0.4 seconds, the obsidian disc grew warm beneath his palm.
---
He pulled his hand back. The Engine's surface temperature had spiked three degrees Celsius. Not much—but measurable. And now, as he watched, it was cooling again, bleeding warmth into the air with perfect exponential decay.
Ethan checked his notes. Found the entries for major energy events: the meteor impact six months ago, the first lightning storm, the ignition of submarine volcanic vents. He'd marked each with Substrate timestamps.
He hadn't thought to check the Engine's temperature.
Now he did the math backward. If the disc had absorbed twelve percent of a volcanic eruption's output, if it had held that energy even briefly before dissipating it as waste heat, then it was converting the Substrate's energy into something else first. Using it. Metabolizing it.
The Engine wasn't just observing. It was *feeding*.
---
On the Substrate, the volcanic eruption reshaped the coastline.
Ethan watched ash clouds spiral into the upper atmosphere, watched pyroclastic flows race across barren stone. The mathematics were beautiful—fluid dynamics at their most violent, heat transfer at temperatures that would vaporize anything living.
Except nothing lived here yet. Just chemistry. Just physics wearing the mask of potential.
He thought about what twelve percent of all energy meant at cosmic scale. The star poured roughly 10^26 joules per second onto the Substrate's surface. Twelve percent of that was 1.2 × 10^25 joules—roughly a thousand times Earth's total annual energy consumption, every single second, vanishing into the Engine.
What could possibly require that much power?
His coffee had gone cold. Outside, Boston was waking up—car horns, construction somewhere, the sounds of a world that ran on laws it took for granted. He pressed his palm against the obsidian again. Room temperature now. Inert.
But he'd felt it wake. He'd felt it *eat*.
---
He started measuring the Engine directly after that.
Thermocouples taped to the surface. A jeweler's scale borrowed from Maya's lab to detect mass changes. A cheap EMF detector from Amazon that probably didn't work but might catch something anyway. He arranged them in a circle around the disc like offerings at a shrine.
Then he watched the Substrate and waited for something big.
It took four days.
The algae mats—still just photosynthetic chemistry, not quite life—had spread across the equatorial ocean. They'd been doubling every few weeks, carpeting the shallows in green-brown film. Now their population crashed. Some chemical imbalance, some metabolic dead-end. They'd evolved into an evolutionary cul-de-sac.
Ninety percent died in eighteen hours.
The decomposition released energy—oxidation, really, molecules falling apart into simpler configurations. Not as dramatic as a volcano. But spread across an ocean, it added up.
Twelve percent of it disappeared.
And the Engine's mass increased by 0.003 grams.
---
Ethan stared at the scale's readout.
Mass-energy equivalence: E = mc². Three milligrams was roughly 2.7 × 10^11 joules if you converted it fully. But the missing energy from the algae die-off was orders of magnitude larger. The Engine wasn't converting energy to mass with perfect efficiency—it was doing something else, something that left a mass signature as a side effect.
He ran the numbers three times. Same result.
The Engine was getting heavier.
He thought about Abel, working in this same apartment forty years ago. Had his grandfather known? Had he felt the disc warm beneath his palm and understood what it meant? Or had he simply accepted it as part of the magic, the way medieval alchemists accepted that mercury was liquid metal without asking why?
Ethan pulled up his oldest measurements—temperature, mass, everything he'd recorded since inheriting the Engine. Then he extrapolated backward.
If the Engine had been accumulating mass at this rate since Abel first activated it, it should have gained approximately forty grams.
He weighed it against a calibration standard. The disc came in at 847 grams.
Abel's journal had listed it at 809 grams when he first found it.
Thirty-eight grams. Close enough for measurement error across forty years.
The Engine had been eating physics since the beginning.
---
That night, Ethan dreamed of the Substrate.
He stood on the volcanic shore, ash still falling like snow. The ocean stretched away into twilight, its surface broken by the dark shapes of decomposing algae. Above him, the twin moons hung in a sky he'd programmed with his grandfather's constants.
And somewhere—not in the sky, not in the ocean, but threaded through the spaces between atoms—he felt something vast turning its attention toward him.
Not the Engine. Something older.
He woke with his palm pressed flat against the obsidian disc. It was warm again, though nothing dramatic had happened in the Substrate. Just the usual churn of chemistry and heat.
The readout on the thermocouples showed a steady 0.2 degrees above ambient.
It had been that way for hours.