<u><em>A major theme of "The Black Cat" by Edgar Allan Poe is violence.</em></u>
Explanation:
Poe uses the device of the unreliable narrator to weave a tale of horror and violence, stemming from the narrator's craven urge to destroy his family and pets.
as for a disadvantage I would say they can be killed by white oak stake and they watch everyone who they love die around them because they live forever