The Doctor's tone is articulate and measured with a soft continential/Belgian accent. His eyes are perpetually hidden behind wire-frame spectacles with mirrored lenses that sit high up on his nose. He is restricted to a peculiar wheelchair, with its tank-like treads, unusual size, and numerous electronic devices connected and built into the chair. He always dresses semi-formally.
The Doctor wields an extraordinary intellect, and a generally affable personality, but is aloof, a little secretive and a recluse. He is an unmatchable problem solver and engineer of many fields, there are very few projects he has ever given up on.
It's unknown what prompts him to accept or reject an ecclectic range of projects. If he's ever asked for payment, his conditions have been kept private.