They're Too Important. They're Too Kind. They're Literal Heroes. I Love Them With All My Heart - Tumblr Posts

I've seen a question going around about when exactly the boys decided to start the agency/what caused them to do it on the first place.

We know it was somewhere in 1990, so it's safe to assume just a few months after Charles' death.

During that time, they found out what happened to Edwin's case, which definitely took a lot of research. And they saw the non-investigation about Charles in real time, which probably meant following people around and checking records.

Not only the injustice about their deaths is what prompted them to help others, the way they went about it showed that they could, in fact, be detectives. They were good at it.

If we consider that, we already know the first two cases they worked on - the Case of Edwin Payne and the Case of Charles Rowland.