Who is Margaillan from The Masterpiece and what is their importance?

Margaillan is one of the foremost builders in Paris, and he achieved this status with hard work and clever business dealings. His selection of Dubuche as a husband for his invalid daughter is based on the fact he believes the man will be an asset to his business. When Dubuche fails at his attempts as an architect, Margaillan relegates his son-in-law to the country where his only duties are to care for his wife and children.