I am writing a story but don’t know how to describe a Space Marine, HELP!
I’d recommend how Dan Abnett describes them in either "Brothers of the Snake" or from the Horus Heresy Trilogy.
But, if I was to describe a Space Marine from the Blood Angel Chapter, i’d start with the basics first. If a normal human or Imperial was introducing the Space Marine, i’d mention how tall they were, how overshadowing their height was. How their voice made my stomach quiver with its reverberating deepness (because of the vox-castor). How their red armour shined like blood, how the black teardrop crowned with the aquilla emblazoned their shoulder guard.
Despite a space marine (in armour) standing roughly 9 feet tall, they move fast. Almost as fast as the Eldar, so their movements wouldn’t be blocky or slow, but almost gracious and full of fluidity.
Without their armour, Blood Angels would have blue eyes (from their Geneseed) and bright blonde hair. Obviously they’d be muscle bound and probably carry massive scarring too.
I’d describe their faces as angular, square jawed/lantern jawed. A noble face but lined in brutality from centuries or decades of warfare.
Hope this helps.