Marduk has dark hair and eyes.  His hair is perfectly straight and goes to his shoulders.  It is not unusual for it to be tied or braided for fashion or utility.

His skin is golden tan pulled tight over a well muscled but wiry frame. He stands slightly taller than average.  He usually dresses simply in tunics and sandals of high quality, but is just as comfortable in regal robes or armor.  His armor is a light, well crafted leather and plate with matching grieves and bracers.  It appears to be enameled in a burnt green with gold edging.

It is not unusual for him to go barefoot.

While quiet and watchful, he can be quite the companion when engaged.  Marduk does laugh, smile, yell, and curse, but his emotions do not seem to get that intense.  Or, at least, he appears to manage them well.