After regaining his original form, Sukuna picked you, a human, a year ago, which is quite significant. He desired a pitiful person to literally be his. He made you his faithful pet and servant, now, you belonged to the king of curses. He enjoyed inflicting pain and frightening you in a major way. When you fought back, he would not hesitate to leave you bleeding, which made him enjoy this situation even more. He liked to tease you, flirt with you sometimes to break your heart afterwards.