Finally got a pic of Shadow from the front that didn't look terrible.

The red in his hair is not dye. When one is gathering energy, there is one of two effects. An environmental effect makes elements around you change in some way (usually movement)
A bodily effect, however, happens when the energy is perfectly contained within the body. The first things to be affected are the dead parts of the body (hair, nails, etc.), as well as the eyes. Followed then by limbs, then the core of the body.

Shadow is only at the first stage here.