A three way vinn-diagram with pirates, vampires, and Princes in the three main circles. At the intersection of pirates and vampires is "classic go-to villains". Vampires and Princes share "living in castles". Princes and pirates both have "stealing from peasants". The shared trait of all three is "wearing these shirts" with a picture of a fancy white shirt with big ruffles on the neck and sleeves.
I made a vampire not wearing that kind of shirt, what now? (Haven't ended up using her yet, as I had to cancel the original work I was planning to use her in - long story short: I was working on that webcomic idea for like 10 years, and many core concepts of it were created when I was a lot naiver)