For those wondering what I'm rambling about, Mara Jade was a character created by Timothy Zahn in a book series from the 90s set in the Star Wars universe after the events of Return of the Jedi. When Luke first meets her, she wants to kill him--she had been trained by the Emperor to do exactly that. However, over time and a number of encounters, Luke finally wins her over. Eventually, the two of them marry and have children (there are some, such as myself, who hoped that Rey was the result).
Her character's story, moving from trained tool of the Emperor (even called the Emperor's Hand) to being a vital member of the New Republic and New Jedi Order, is one of the more interesting character arcs in the entire Star Wars universe. Unfortunately, Lucas himself began to dismantle the complex "history" that other authors had been allowed to build through novels and comics when he released his prequels. There was some hope that Disney would nudge back into the direction of the "Expanded Universe," but most of that speculation was dashed with The Last Jedi.
Honestly, some of the novels went a bit off course themselves. Still, Timothy Zahn's contributions, Mara Jade in particular, were masterpieces. It would have been wonderful to see her on the big screen. I know I shouldn't, but I'm still kind of hoping we will see some sort of nod towards her in The Rise of the Skywalker this Christmas.