The Blue Rivers

Tszuvok was the one who noticed it. He was sanding a plank in Crivsola's workshop, and the afternoon light was falling across the back of his hand at a low angle. He paused and turned his hand over.

"Have you ever looked at these?" he asked, holding his hand up.

The Lines

Blue-green lines ran beneath the skin on the back of his hand, branching and converging like the tributaries of a river seen from a hilltop. They were faintly visible even in dim light, but in the afternoon sun they stood out clearly — a network of channels, right there on the surface, in plain sight.

Crivsola stared. She turned her own hand over. The same lines. She pushed up her sleeve — the lines continued along the inside of her forearm, larger now, more prominent.

She pressed one of the blue lines with her fingertip. No pulse. No rhythmic throbbing. The line was soft and yielded easily under pressure. She could even push the fluid along it — press down and slide her finger, and the line went pale ahead of her finger, then filled back in when she released it.

Two Types

Now she checked the places where she had found the pulse — the inside of the wrist, the side of the neck. She pressed carefully. The throbbing channels were deeper. She could feel them, but she could not see them. They hid beneath layers of flesh, tucked away, protected.

The blue lines on the back of the hand were different. They sat close to the surface. They carried no pulse. They were visible to the naked eye.

Two types of channels. The pulsing ones are deep and hidden. The blue ones are shallow and still.

This was exactly what the Loop Model predicted. Outgoing channels — carrying fluid under pressure from the pump — would pulse with each beat and would logically be buried deep, protected from injury. Return channels — carrying fluid back at lower pressure — would be quieter, calmer, and apparently did not need the same protection.

Confirmed

Crivsola felt a particular kind of satisfaction. She had not gone looking for the blue lines. She had built a model — the Loop Model — that predicted the existence of return channels. And then the return channels had turned up, unprompted, on the back of Tszuvok's hand.

When your model predicts something, and you find it without having to force the evidence, the model earns trust.

Tszuvok mentioned that the lines became more visible after drinking Grtizki — the sweet fermented drink sold at every tavern in the market district. Crivsola noted this. Whatever Grtizki did to the body, it seemed to make the return channels swell or move closer to the surface. She filed the observation away.

The Map So Far

She drew the picture as she now understood it. A pumping-thing in the chest pushed fluid outward through deep, pulsing channels. The fluid traveled to every part of the body — delivering the fuel that muscles, frame-pieces, and everything else needed to function. Then the fluid returned through a second set of channels — the blue rivers visible under the skin — back toward the chest-pump, to be sent around again.

A loop. A circuit. But she still had not seen the fluid itself. She knew the channels existed. She knew something flowed through them. She did not yet know what it looked like.

That question answered itself sooner than she expected.