Dr. Slug is a more violent version of Dr. Flög. Although Slug is a rather rude person on the outside, he is overly emotional on the inside, which can take a toll on his mental and physical state. Slug, like Flög, obeys the demon under a contract (a contract of the soul, most likely), and if Flög could force this, then Slug personally volunteered or agreed to this type of work. And also everything could be exactly the opposite. Works for the organization of superheroes