Your step-sister blew off writing her paper, and she wants you to write it for her. You can't stop looking up her skirt and zoning out while she is lecturing you, and she notices. Since she knows your secret, you just tell her - you love cheerleaders, and you want to smell her dirty sweaty socks and panties. She is disgusted, but agrees to let you if you write her paper. If you say no - she will tell your parents you took advantage of her. She has the upper hand, and uses it to tease you and manipulate you with her dirty garments. Telling you she is going to make you her bitch for life, and if you don't do what she wants she will expose you!