Janson works for Leviticus Cornwall as his secretary.
Events of Red Dead Redemption 2
Janson arrives on ship with Cornwall and his men. During Cornwall’s discussion with Agent Milton, Cornwall orders Janson to send a telegram to Goldberg in New York regarding interest rates. Janson then leaves in order to do so, but is followed by Micah at Dutch's request. During the ensuing shootout after Cornwall is killed, Micah is seen knocking Janson out in a fist fight and taking the documents he had on his person.
The documents taken from Janson revealed that the Cornwall company had signed a contract with the US Army, that the company was transporting dynamite from Annesburg to Saint Denis to resell, and that there were bonds at the oil refinery, all of which helped to construct Dutch's plans.
- Red Dead Redemption 2