It doesn't seem like there's really that much to the character does it? He just seems out to get Frank. He just seems kind of like a thug in general. And he's kind of a coward too. But I love Jigsaw stories. But what really did it was him having slashing up his (Retconned in.) sons face. Pretty cold. When was it revealed that he took part in the murder of Frank's family? THAT right there makes him the Punisher's arch-enemy,
He's absolutely a sadist.
Other than slashing up his sons face, he also did the same to Frank a number of years ago. He's known to be a wife beater, and just one recent example of his sadism is when he convinced Frank that his wife was resurrected and determined to kill him, and then engaged in a sexual double team with her with Stuart Clarke live on camera for Franks viewing pleasure.
I think its pretty safe to say he loves inflicting pain and misery on others.