Yes! Dark Empire. I thought it was a Zahn novel, but you are right. It was the cloned Palpy comics.
In general, I feel like there is so little information about backstory, intentions, character arcs etc. But I recall the same thing when ESB came out. I was like WHAA? Why is Luke so intent on not killing Vader? What makes Luke think he needs to toss his lightsaber aside? Yoda did not teach him that, and Aunt Beru is not portrayed as a great bestower of gentle wisdom. Maybe Padme came to him in his dreams?
My point is that so much about Vader was revealed in the prequels that explains the seemingly inexplicable end of ROTJ. Why on earth would anyone, especially Luke, think there was even the slightest chance in hell that Vader would do anything except follow the Emperor/try to become Emperor? What clue is there ANYWHERE in the OT? I was totally confused by this at the time. Only after 30 years of backfill does it kind of, sort of, slightly, make sense.
So what does that have to do with this thread? Well, I am suggesting that there might be a lot more going on in THIS situation as well. We just don't have the backfill yet. Who would have thought Vader was really a nice guy ... deep WAY WAY DEEP down?