Basic Trope: A villain that starts out as nobody special, but years later is one of the most dangerous people in the world.
Straight: Jadal was originally just a poor man, who ended up with a dangerous artifact that made him all-powerful.
Exaggerated: Jadal was once someone's pet hamster. Now he's usurped Satan and working on doing the same to God.
Downplayed: Jadal was once a middle-class drone, but has since become the head of a crime ring
There were incredibly harsh conditions, prompting the change.
Jadal was one of those people you never really notice day-to-day. As such, nobody was worried about what he might do until it was far, far too late.
Anything can happen to anybody. Jadal happened to be a nobody who came upon something that really allowed them to change their life, but seeing as they were mentally unbalanced, strongly or not, they ended up using the change to become something horrible.
Jadal was originally a poor man, but later becomes the Big Good, or even The Hero.
Subverted: His backstory isn't as bad as it seems, and he seems like a decent enough guy.
Double Subverted: He's still incredibly dangerous.
Parodied: Jadal went from a normal office worker to a Physical God... and everyone either doesn't notice or care.
Zig Zagged: Jadal was once a poor man, who ends up with a dangerous artifact that makes him all-powerful, but is beaten by the heroes, who confiscate it. But Jadal refuses to stay a nobody, so he learns magic and becomes a powerful sorceror even without the help of the artifact.
Jadal was a generally fearsome person to start out.
Jadal started out small and ended it small, with small in no small amount in between.