Who is Colum from Daughter of the Forest and what is their importance?

Colum is a seventh son of a seventh son. He inherited his family home because each of his six brothers was killed in combat while protecting their homeland. Colum's calling was to be a druid, but he fell deeply in love and was passed over. Colum's love for his wife was absolute and enduting. Thus, when she died, he was devastated. Colum is described as a strict, dispassionate father, who wants his sons to be warriors.

Over the course of the novel, Colum falls under the spell of an evil witch, Lady Oonagh and brings her home to become his wife. He is so deeply under her spell that he will not heed the warnings of his sons or his priest. When he marries Lady Oonagh, bad things begin to happen at Sevenwaters, culminating in the disappearance of all seven of Colum's children. Devastated, Colum goes insane. When his children later return, however, Finbar helps him to restore his sanity.