It's not directly related, but there's a lot of in-jokes and references to DMC in Bayonetta, such as one character who has a relationship with Trish, the Eva thing and Enzo's involvement. It's made by Hideki Kamiya too, so I like to think they're related. The game is really good if you're into hack'n'slash games (like DMC) but don't try to follow the story on your first playthrough. It's crazy.
I've always imagined this as Sparda flitting back and forth between the (at the time) primitive human realm and the demon realm. After it was over, Sparda spent 2000 years in the human realm, in human form. At one time he even ruled the realm. Then eventually he met Eva and begat twin sons, you know the rest.
Fun fact: I once tried my hand at attempting to reboot the franchise and had settled on setting it in the Georgian era, with demons feasting on the remains of British soldiers. It was pretty cool.
Yeah, I get the tone you're looking for. With the love theme and the Victorian/Georgian setting, might I suggest giving it a book-like design?
Something similar to these I think would work quite well. It would be very difficult to implement though. If you're looking for a more conventional cover, I can give you
this image of Sparda (rendered by .:*Dante*:., please give credit to him if you're going to use it.) I could also try my hand at making some screenshots if you want.