Vader encountered a Jedi who clearly leaned towards the dark side of the Force. He felt drawn to this powerful source of energy.

For Vader, fighting this Jedi was like fighting his own reflection in a mirror.

Vader saw the potential of this Jedi and saw in him the possibility of creating the perfect inquisitor — someone who would stay by his side and help him achieve his goals..

The dark side was like a drug for him.

"This fight will be interesting..." He said darkly.