Born into privelage, Marcus had no problem entering a prestigious medical school - though he did graduate with honors on his own merits, having cut most ties with the backwards-looking old money that had spawned him.

A promising career in research clinic and drug testing was before him - a pharmaceutical firm that was a subsidy of the mighty Cheiron Group had hired him eagerly, wanting to use the talents (and the cold, ambitious personality they've found in younger doctor Weiss) to their advantage.

Another opportunity had presented itself, though - the good doctor's younger brother had fallen into the worst possible crowd when he was in colleage, and, as Marcus found out, had fallen a victim to a haematophage. Cheiron once again approached the prodigal researcher, and revealed the hideous demimonde of monsters lurking just beyond the lights of human dwellings - and a chance to take revenge on them.

And thus, Marcus had been entrusted with producing thaumotechnological marvels from the flesh, blood and brains of the monsters he and the group of street-level hunters manage to haul back to the hidden laboratories. He feigns that his interest in the hunt is purely clinical, but... there's a certain cruel streak he has when he directs the hunts against vampires, sometimes not even bothering with securing the body and instead burning it to cinders, and using the ashes and bones that remain.