Body of Wavering Fire

Your soul is not that of a mortal, but that of flame, because fire is merely another form of life. Fire's shape, color, and brightness change constantly, as do the people with this feat. 

Fluctuating Form. You can change your form as outlined in the Change Appearance option Alter Self, but this effect is permanent and becomes your "base" or "true" form until you use this feature again. You can use this feature up to your proficiency bonus per long rest.