This is not the fourth movie, and this isn't lycans experimenting with vampires. It's the other way around. For this rp, I'm vague on the direct descendents of Marcus and William Corvinus. Leo is creating these creatures, he doesn't know why some die and why some don't. Since we're farther back in time than the fourth movie, more like the third one, there are more direct descendants that are able to hold both strains of DNA, if you will. 
I already have a non-lycan, non-vampire character, sorry, it's a no go.