The King of Rhodia was Charlie's father, and husband to the Queen. (TV: Co-Owner of a Lonely Heart) The King of Rhodia was killed by a Shadow Kin, along with the rest of his kind. (TV: For Tonight We Might Die)
He and the Queen never saw Charlie as someone worth bothering combining with, instead as a valuable piece of property to be used for the good of the country.
In 2016, the Lankin briefly attempted to present itself to Charlie in the form of his parents, but, as he later explained, he didn't have a strong enough connection with them. (TV: Nightvisiting)