I always looked at the dark side as a means of power and control. Control and power over others.

There was a line somewhere in the ROTS novel where Palps further seduces Anakin by promising him a whole star system. It's those kind of things that would go further in the seduction as a quest for more power and control.

This goes back to AOTC and his inability to let things go and his need to control where people are and what they're doing. He puts R2 in Padme's room to watch her. He dreams and obsesses over his mother's fate.

It's like the old saying: the road to hell is paved with good intentions. His original intent may have been noble, but misguided. By ROTS, it should become simply power for power's sake.

It should be like him slowly becoming addicted to the power he thinks the dark side will give him.