The personality of the killer dictates how they operate. The reason why they kill. How they kill. The drive of the kill. Who they kill.

The theoretical situation you posed, I'd would want my partner to be a serial killer as well. But I don't necessarily want us to work together. We could team up on certain things, but I think we'd want to do are own thing separate thing and them come home to talk about what we did at the dinner table. If I was a killer, I'd have to pretend all the time outside that I was normal. I'd want to be able to not act while home.

Haha, I'm glad you'll be wondering about invisible men now.

Wow, it's a good show to take over Supernatural.