Legolas is the Crown Prince (probably). He is generally considered to be uninvolved in his father's wilder moments but it's a bit more than just being his son. Son and Heir in a setting that's big into monarchism.

I think Tolkien would probably argue that doesn't make him an instrument of the state, necessarily, but Tolkien also thought anarcho-monarchism wasn't an oxymoron and refused to tell us about Aragorn's tax policy.