Delightful tale.
I do have something I'd like you to think about. My mother has Althimzer's.
When my father was in the CCU a couple of years back we found that we could not let my mohter visit him because while she would forget what was happening the bad mood it engendered would last for hours after she'd forgotten.
Perhaps Lex's mood would be altered just a bit and he would decide to kill Superman PRIOR to the wedding.
Perhaps your historian will return to an altered future.
