Who is Luykas Schoonmaker/The Master from Confessions of an Ugly Stepsister and what is their importance?

Luykas Schoonmaker is the artist who takes Margarethe's family in off the streets. He instructs Ruth to gather flowers for him to sketch, Margarethe to cook and clean, and Iris to sit for him to paint. He seems gruff and unapproachable at first, but soon they learn that he is lovable and kind beneath his forced, coarse exterior. The Master has a reputation for painting people with physical abnormalities that he puts in the Gallery of God's Mistakes. He falls in love with Margarethe, but she will not marry him as he is not rich. He wants to paint religious figures, but there is no market for that in his area.