Vladius said:

Sepharih said:

I'm saying that there should be more established and better developed motivations for Luke's near turn.....and you're saying that it's the emperor's power of persuasion in the force that defies rational.

There are, you're not seeing them.
You think that he's turning to the dark side when he attacks Vader, he's not. He's angry at the idea that Vader will try to turn Leia, along with everything else that happened, but that's the thing that makes him actually start attacking. It's well established already that they love each other, romantically or platonically, in all three of the movies. In the same movie, Luke has rescued Leia and showed concern for her well being. There is a scene where he tells her that they're brother and sister.

His "near turn" is within the duel after he starts attacking, when he goes from participating to becoming the aggressor. This is because he is using his anger to help him succeed, which has natural consquences that are also well established. That's why he looks surprised and disturbed with himself after cutting off Vader's hand. He's realizing that he's gone farther than he intended to.

This.

A turn to the Dark Side (in the OT) is not described as a simple choice based on wanting a specific outcome.

It's seductive, and easy. Dangerous.

Luke's "motivation" is getting him pissed off/scared enough to use the Dark Side. "Why" doesn't matter. (There is no why).

The Dark Side isn't steroids. It's not a shady choice that leads to a goal.

The Dark Side is methamphetamine. Try it and it destroys your soul and takes control.