"To help me with this assignment..."

While on the way to my girlfriend's house, I met a beautiful girl. Since she couldn't catch a taxi, she asked me to take her home. But I didn't expect that she was actually my girlfriend's older sister who had just returned to the country!!! After taking her to her place, she wanted to thank me in a foreigner's way, and not knowing what it was, I agreed, but I didn't expect her to thank me with..

. sex!!! I was tempted by her, she had a huge "soul", and allowed me to not use a condom, things my girlfriend never allowed...