You suddenly feel a strange sensation above your bottom. A sensation that was quite familiar. You grown slightly as your tailbone shifts and adjusts and you feel a long hairless appendage grow right beside your original tail. You look behind yourself and watch as the long appendage quickly starts growing black fur like your other tail. Soon enough you realized you had two tails!
You examine your new tail with a mixture of excitement and confusion. Why now? Then the world answers. Your stomach starts to growl heavily as if you hadn't eaten for days.
You clutch your angry stomach and realize what had happened!
Over the course of you being a demon fox, whenever you had eaten a soul, you weren't exactly eating it, but more like storing it. Storing it for a use like this. Growing a new tail.
Your inherent demonic knowlege told you that kitsune or foxes were incredibly special. Over time they would grow another tail. The more tails a fox has the more powerful it is. The new tail signifies that you had grown more powerful.
Humans had usually there were only seven of the Seven Deadly Sins, however two more secret sins that only angels and Demons knew of existed. They were:
Ambition: Ambition was usually a good thing to have. However those who set aside everything else for their goal. To mercilessly harm others just to inch closer and closer to something, not caring of the consequences is to have the sin of Ambition.
Betrayal: To lie and betray. Those who break their promises for the worst of reasons such as being n bribed or killin those they were supposed to protect is to have the sin of Betrayal.
You knew that your first tail represented the sin of Envy. Illusions, shapeshifting, turning invisible. Those were all powers that Envy granted you.