E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Predestined to early death. When a person suddenly changes his wonted manner of life, as when a miser becomes liberal, or a churl good-humoured, he is said in Scotch to be fey, and near the point of death.
She must be fey (said Triptolemus), and in that case has not long to live.Sir W. Scott: The Pirate, chap. v.