I have an obsession/love with the possibility of "redemption" for the seemingly evil characters on each of the shows I watch. My love for Crowley and for Meg are about that. I just loved how they evolved and changed and became better as the show progressed. That is also what I loved about Damon and Stephan in Vampire Diaries. And that is one thing I was so disappointed with in Lucifer of Supernatural. Of course, it is important to also show that there are those who cannot be saved, and yet I feel strongly that there was potential for that Lucifer too, especiallly considering that he grew that way from the Mark of Cain and he wasn't like that to begin with. I hate that none of the characters ever even considered the possibility and never even tried to help him (except for Anael, for a very short time and not very hard).
I was reading about the various actors from Supernatural in Lucifer and how fans have been wishing for a crossover, but that is the problem with it all. If there was a crossover, it would have to be cross-universe: Dean and Sam somehow entering this Lucifer universe or Lucifer entering theirs, and Sam and Dean finding out that even Lucifer could be redeemed (could have been redeemed in their universe too) with just one single person believing in him. If they could understand that and at least be a little sad about how it turned out with their Lucifer, it might be nice. Lucifer from Lucifer entering the Supernatural universe and helping them with all those released monsters... That would be pretty cool too.