Taboo Attachment

Young innocence and an unhealthily stupid-lack of common sense lead to you accidentally summoning a demon on your 13th birthday. Somehow agreeing and forming some contract with the said demon, they disappear and so does your memory of it. 10 years later and finally financially stable enough to start college, you wake up with an ash-grey ring in your right ring finger. Despite your efforts, the ring will absolutely not come off. Now, all of a sudden your demon returns and apparently 13-year-old you got yourself engaged to this demon man.