Thoughts about Luke in TLJ (Spoilers):
I’ve never read any comics or books about Luke but I got the feeling that there must be things that affected Luke that even he was overtaken by the fear of the dark side for a moment.
I mean, everyone thinks Luke is this perfect hero, that he can’t have any darkness, but he is only human, and he was researching things regarding the Jedi and the Force after Episode 6. He only had himself to
consultant
about an ancient religious system and it’s philosophy. Not to mention that the light side and dark side force temples can actually affect people. Even the Jedi temples are not “friendly“ and it’s shown in the cartoon that padawans would actually die if they fail the temple’s test. I kind of suspect that Luke was unknowingly being affect by the temple he opened school in, maybe he was dealing with the influence of the dark side himself, and after fully knew what kind of terrible things his father had done, it makes sense that he would be afraid of the dark side to the point that he was tempted to kill Ben when he’s being wavered by Snoke.
I mean everyone kind of brushed off Vader as “he’s once good, but he turned evil” to Luke in the old movie, it’s understandable that Luke’s thoughts about Vader was more simple and he wanted to save Vader. But if Luke dug out more Jedi history or knew the extend of Vader’s “turned evil” means to the whole galaxy, he would probably felt conflict about it (did he and Leia ever talked about it in any of the novel/comics?)
There is a huge character gap between Episode 6 Luke and pre episode7 Luke, I don’t think it is impossible that Luke would have some dark thoughts but there should be some developments/hints in between.
My grammar is terrible I should stop lol but this is my take on Luke’s behavior.
I’d watch a movie about Luke after Episode 6 and is played by Sebastion Stan.