I've been drawing Penitence for a looooong time in my personal sketches.

Growing up, Shadowbeasts are how I imagined deep or persistent negative feelings would look. Everyone has a pack of Shadowbeasts, each member representing a powerful emotion their person grapples with (shame, rage, loneliness, despair, anxiety, jealousy, etc). One (or more, if you're really struggling) follows you around as your shadow, feeding on your actions and energies. Depending how well they're fed, they wield more power and influence. Usually only the most persistent Shadowbeast of your pack stalks at a given time, and no two are the same. Even if you and another person both have the same type, yours is unique to your own struggles and the ways they affect you.

Penitence, my Shadowbeast of Shame, is a particularly nasty bugger.