Who is Roarke from Immortal in Death and what is their importance?

Roarke is a mysterious, Irish businessman, who owns most everything in New York City, and is a business broker for many entities, including several "off-planet" business deals. Roarke is handsome, smart, very wealthy, and knows when to invade Eve's space and when to allow her to be an independent woman. For many men, being the husband of a homicide detective could cause a great inferiority complex, but Roarke is completely at ease with who he is and does not derive his self-worth from anyone but himself.