Freeborn is the Valornian term for any child born to parents that either belong to different Houses (usually the result of illicit affairs), or that are themselves Freeborn. Even if one or both parents are Trueborn, the child will still be considered a Freeborn.
A Freeborn is forced to live or die on their own merits. Even if their mother or father acknowledges the parentage and takes the child in, the child will still be regarded as a Freeborn. As a result, Freeborn rarely advance to high position, but those few that do are certain to be experts at what they do, simply because they could not otherwise advance.
Almost all Freeborn is raised to regard all Trueborn as superior beings, and are expected to show obedience to any Trueborn. The fact that all Trueborn is raised to regard all Freeborn as inferior beings makes the life of a Freeborn even more difficult.
There is one redeeming factor about Freeborn, however. Any Freeborn could - in theory - be elevated to the rank of House Patriarch, thus becoming Trueborn by default. Any legitimate children of his (or hers) would also be Trueborn, thus founding a new House. Unfortunately, the last time that happened was 70 years ago, when Wolmar Brandt was allowed to found House Brandt.