Willy is a character that can be found in the Broken Valley during the events of Divinity II: Ego Draconis and later on in Aleroth during the events of Divinity II: Flames of Vengeance. He is the author of the book How to Pull a Willy (and get away with it).
Divinity II: Ego Draconis Edit
Willy is a 'house salesman' who you run into three times in Broken Valley. Every time he tries to get you to "invest" 500 gold in a house that is "for sale" in Broken Valley. Don't fall for this trick! You can mindread him for 400 exp to learn where he hides his stash of gold. This stash does not include any gold that you have given him, and is located behind Yup'ik's Totem.
Divinity II: Flames of Vengeance Edit
You will meet Willy again in Aleroth west of the Great Market waypoint shine (see Aleroth map), where he asks for help to get rid of some assassins at his house on Lanilor Lane as part of the quest A Swindler Swindled. You can mindread him to find out that he has played a trick on the player character before (even if you didn't fall for his scam in Broken Valley); this is not worth the exp cost. You can put off the quest by asking for funds to buy better armor, then better weapons, then potions, to receive 500 gold each time for total of 1500 swindled from him.
You may encounter him a final time if you side with Behrlihn. Willy will attempt to run a con on Behrlihn after his release and get turned into a chicken after his con backfires (he apparently won ownership of the vault that Behrlihn's prison is in from Deodatus in a card game, and tried to get Behrlihn to pay a thousand years worth of rent).