Source: CoS (Who's Who in Waterdeep) p.18
In his youth, Ultas was a mercenary and committed numerous atrocities against southern villages in order to make money for his family. He took up a lordship in Waterdeep, abandoning his past life, but was consumed by guilt, which caused him nightmares.
He had a wife and several children, but they all died in the plague in Amn in 1345 DR, leaving him with no heirs. After this, Ultas became a recluse and saw few people, save for High Priestess of Selûne Naneatha Suaril, who helped him recover from his grief and encouraged him to take up religion, Selûne in particular. During this time he began donating generously to several Waterdhavian temples.
Ultas refused to marry again after the death of his wife, and had no children and therefore no heirs. He was permitted, upon his death, to donate his fortunes to the Lords of Waterdeep who would spread them equally amongst the ten major temples and the Plinth. The Maernos family home would also be converted to a place of refuge and worship for non-human inhabitants of Waterdeep. He began this conversion himself before his death, purchasing art such as paintings and statues appropriate for non-human races.