Furor and Occasion are one seriously terrible twosome in Book 2. Furor, who's named means "fury," embodies the passions of anger, vengeance, and violence gone completely out of control: Furor fumes and glares and attacks without reason or judgment. His companion and aid, Occasion, embodies how we actually create situations in which our anger can get out control.
For this reason, Guyon wrestles with Furor endlessly, without success, until he first binds Occasion: anger is best prevented by controlling an occasion for it. This can be tricky, however, as is symbolized by Occasion's bizarre hair, which grows in front of her face rather than behind her head. Why? Well, if you want to control Occasion by her hair, you have to do before it happens, you can never do it after. Essentially, it's just representing the fact that once an occasion has happened, it's too late to reverse it.
The threat of Furor and Occasion are particularly important in Book 2, which is dedicated to temperance and to avoiding the kinds of explosions of anger and feeling embodied by Furor and enabled by Occasion.