At this point this is still a very rough thesis, but I think I finally have one that is able to move forward. So I've mentioned in previous blog posts that I'm interested in looking at archetype of the "overreacher" in Milton's Satan. Milton certainly didn't invent the overreacher, though his Satan has come to be perhaps the prime example of one, such that it would influence later works like Mary Shelley's Frankenstein and Byron's Manfred. So here is my working thesis (more or less): Milton followed the literary tradition of the overreacher (as seen in works like Marlowe's Tamburlaine the Great and Doctor Faustus, Shakespeare's Macbeth, and the story of Icarus) in order to use it as a template to represent his personal experiences and the historical context that he had lived through. It's interesting to look at Paradise Lost through the lens of the Cromwell, the Interregnum, and the Restoration.
This is what I have currently as far as a thesis. If anyone has any research that they think might fit well with this, please let me know.