Lord Mortimer (aka Paul) is the main antagonist of Charlie Murder. You fight him in a boss fight twice in the game.
The boss fight is fairly straight forward. The Wiki for the game has a pretty basic walkthrough for this fight. https://charlie-murder.fandom.com/wiki/Paul_Bitterman
I'm going to supplement this with two videos from YouTuber "October Monkey." One shows the Phantom Paul boss fight and the other shows the Lord Mortimer boss fight for context.