I think my teen sister is a selfish little brat.
Why do you feel she is a selfish little brat?
My parents has decided to give her all one-side love. I know she's a mother's daughter, but it's also about me. I too want all the love my parents can give me.
You shouldn't be selfish of your siblings. If you want more attention you need to let your parents know how you are feeling.
Why don't I just tell my sister how I feel. I'll tell her I hate her.
Hating your sister for your parents behavior is just going to make you both miserable. Instead, talk to your parents and let them know you feel unfairly treated.