I was thinking of butterflying the treaty of Goulet in 1200, I think after the divorce between the King of Leon and Berengaria, I think a marriage between Louis VIII and Berengaria is possible in 1205 if the Treaty of Goulet was not made and Berengaria is the heiress to her mom's claims to Gascony and it can be used as an excuse to conquer Gascony.