Ardyn massively fucking up his plans by actually falling in love with Noctis. He doesn't have to be redeemed but maybe becomes less of a murdery asshole?

+ Ardyn is really pissed off about the whole thing at first.
+ When he comes to terms with it theres some really awkward flirting.
+ Noct is totally clueless for the longest time.

OR If the filler were so inclined they could make it full on angst filled tragedy and that would be cool too.