These are the emotions the Sin expresses with his tail involuntarily.

Upset: Angry, Upset, Unsettled, or he's just walked into an unsettling situation.
Like a dog crap. His tail will flicker upwards and twing unpleasantly.

Attention: Amused, intrigued, Fascinated, Excited. His tail will woosh back and forth,
usually lifted from the ground a little. What ever it is has his attention.
He might be getting himself into some fun mischief.

❤: Desire, Pleasure, Excitement. His tail will curl upward and sometimes around
itself grasping at the air. Sometimes it will wrap around the nearest object.
He finds what is happening rather pleasurable or something he wants in such a way.

Neutral: Calm, Relaxed, Level Headed. His tail hovers above the ground, often times lightly
wagging the end of his tail from time to time.

Taunt: Aggressive, Annoyed, Defiant, Confident. His tail flicks upward as if he were to have
flipped you off. He's ready to fight at any time.

Down: Sad, guilty, unhappy, nervous. His tail hovers just barely above the ground.
The situation he's in is rather troubling.