"You're studying ...us? Humans?" Well, Humans, yes. You, on the other hand are not quite human." How can that be? I have a child, so obviously I must ...be human." We ... added a few modifications to you when you were just a toddler.So we could recover your memories, to help us understand humans better." I ... see," I replied, then added, "You said something about the lasttime you were here?" Yes, some things were happening for you that meant we wanted to do morethan just get your memories this. I ran around the bed with my towel and stood in front of her chair ready to swing at her, but she was lashing her towel back and forth so fast I couldn't get close enough without getting hit. Just then I caught her towel and held it so she couldn't move it. She tried tugging it from me, but I held tight and then pulled hard forcing her down from the chair. She let go of the towel, shoved me backwards with her shoulder and dashed past me."Think you can catch me," she taunted, running to the. ....The next morning she came in the bedroom completely naked and we fucked all weekend. It was interesting because I noticed she would only suck my cock when her pussy juices were on it. She also loved my ass and would eat me and finger fuck me a lot. I still could not believe that much sexual energy could come out of that little body, I honestly thought she could dress up and pass herself off as a middle schooler. We developed a routine over the next several months where we would go out. I made it safely back into my own room of course, closed and locked the door, then hurriedly stripped, jumping into bed holding my sister's panties in hand. I carefully examined the crotch, saw the telltale stain of her female secretions, and then placed her soiled panties over my cock and began to pleasure myself. I enjoyed the feel of the silk-like material as it caressed my prick. Another reason I enjoyed masturbating myself with them. But I also had the mental stimulus of soon adding my own.