My stepbrother thats 1 year younger is pissing me off?

ive known him for about 9 years and i dont mean to b*tch, but he is stealing and copying everything that i like and do and say. he just told me "piece bruh" when he left to go to his moms. THAT IS MY PHRASE. he is wearing the clothes i wear. he is "liking" the bulls and the nba even when he doesnt even know the coach for the bulls. its just pissing me off cause i like to be unique. the worst is my music. he NEVER used to like Kanye west or lupe fiasco. he didnt even know who they were untill this year. it just pisses me off cause he is asian and im puerto rican and he tries to rap songs like monster and power. thats not for asians to rap!!! he sounds soo terrible when he does. its SO IRRITATING. he terrible at singing too. he tries to sing songs from my fav r@b artist musiq soulchild. like i said, i like being unique, and he isnt letting that happen. WHAT CAN I DO TO MAKE HIM STOP?