As Jean Froissart records, Fébus was betrayed by his son who also bore the dynastic name, Gaston, and who tried to kill his father using poison given to him by Charles II of Navarre.
Fébus caught his son in the act and imprisoned him.
In a subsequent violent quarrel, Fébus stabbed his son, who died.

Following Gaston's death, Fébus had no legitimate descendants.
In 1393, in Paris at a masquerade given by the Queen of France, Isabeau of Bavaria, one of Gaston Fébus's four recorded illegitimate sons, Yvain de Foix, was burned to death when his costume, along with the costumes of four others, caught fire from a torch at the Bal des Ardents.
As Jean Froissart records, Fébus was betrayed by his son who also bore the dynastic name, Gaston, and who tried to kill his father using poison given to him by Charles II of Navarre. Fébus caught his son in the act and imprisoned him. In a subsequent violent quarrel, Fébus stabbed his son, who died.
Following Gaston's death, Fébus had no legitimate descendants. In 1393, in Paris at a masquerade given by the Queen of France, Isabeau of Bavaria, one of Gaston Fébus's four recorded illegitimate sons, Yvain de Foix, was burned to death when his costume, along with the costumes of four others, caught fire from a torch at the Bal des Ardents.
Gaston III, Count of Foix