Lord Donal was a thief and, along with Reuben, was one of the two leaders of the Downwind Thieves' Guild. He lived in a mansion in Downtowne[Fact Check] which was connected to the Overlord's Fancy and Reuben's mansion via a network of sewer tunnels and underground passages which served as the headquarters of the guild.
Around the time Garrett broke into Ramirez's mansion, the Downwinders robbed Lord Randall's of his vase collection, including his prized sapphire vase. Donal and Reuben disagreed on who would receive this vase, which was worth more than the rest of the score combined. For the time being, the vase was kept locked in the safe in Donal's mansion, while the key was kept in Reuben's mansion. (TG: "Thieves' Guild")