Techmarine Gastellus during his education on Mars.
Personality: grim, enigmatic and reclusive
Weird stuff: loves to rape AIs with his mechadendrites, pyromaniac
Obsession: spare parts (he collects them _everywhere_), holo-porn movies
Favorite weapons: flamethrower, power halberd
His armor is heavily modified even by Mechanicus standards. Gastellus used forbidden Necron technology to make it very durable and self-repairing. He also installed a set of anti-gravity generators. It happened after one of the students fell off the maintenance pit's edge and crashed into bloody pulp.
His real love is to build fortifications. He adores sentry turrets, mine fields, camouflaged bear pits and other defensive constructions. It also makes him a perfect 'lock pick' to any fortified enemy position.
His personal vehiculum is the insanely-modified 'Giga Gear' Land Rider. Alas, Gastellus is on bad terms with it's machine spirit, so usually he uses plain Predator instead.
Gastellus favors Slaanesh. Not to the point of forsaking other chaos gods, but he definitely leans towards that spoiled deity. That's why, after joining a warband, he took Namiel (that slaaneshi ex-Blood Angels sanguinary priest) under his protection. Dirty rumors were born among their fellow chaos space marines, but Gastellus was faithful to the only big love in his life - a mysterious Tau AI.