Dessier Hahlsner Arls is a character from Atelier Meruru: The Apprentice of Arland.
Dessier has long had issues with his daughter, who does not fit the normal model of a princess and often seems to flit uncaringly from one interest to another. He initially disapproves of her intention to become an alchemist, but after realizing her commitment, agrees to let her continue providing she meets a clear goal. His disapproval stems from his sister Sofra dying while studying alchemy.
He gives Meruru three years to fulfill her royal duties to develop the kingdom. If she fails to bring up the population by the end of the three year time period, she will be forbidden to continue working as an alchemist. If she does succeed, however, he allows her to continue studying alchemy. He realizes that although not conventional, this is Meruru's way of fulfilling her royal duties.
He stays in the throne room for the entirety of the game. He will speak to Meruru briefly in few cutscenes and is seen at the end of the game during the merger between Arls and Arland. After Airshatter awakens in Year 4, he will give Meruru a recipe book that contains the recipe for the Rime Crystal, which is required to stop Airshatter from destroying Arls.
He entrusts Rufus to care for Meruru and to help her achieve her goals.