I would also like to learn more about Gortash's past and how he got chosen by Bane, he is one of the main antagonists, would be nice to get more background on him. Hopefully, in the Definitive Edition, Larian will include the Upper City to bring some character stories/quests together. The game has so much potential to become even better if they take their time working on restoring some cut content and implementing newer content.
And I believe Mephistopheles is indeed Raphael's father. I think Mephistopheles gave Harleep to Raphael to keep him distracted from causing him problems.
