Okay, so I've a lot of siblings. Lots. Couple of brothers, couple of sisters. But only one catches my eye so much that I'll exclude all the others, and it's not for... for healthy reasons. See, I like to think of myself as a guy who puts his family first. So when they were going on a holiday, I was like 'eh, I'll watch the house!' I didn't expect her to say so as well. So, I was stuck at home with my sister, and it's not hard to explain why I'm so enamoured. For starters, she's my step sister. Step Dad's daughter. She's not too tall (But then, a lot of people are shorter than me) and she's so very, very well developed. Large breasts (D cup at least I reckon, though I'm not good at guessing by sight), delicious ass, and she's very pretty as well. Long pale blonde hair. She likes talking to her friends on her phone and stuff, rarely came out of her room. But she's so fucking perfect. The others were gone for a month. So Four weeks. And in the first week, I found myself (Bout midway through the week) on the same mattress as her. It was late, almost midnight, and she'd never been good at being awake late. She'd clocked out while we were watching Arrow, second Season. She was wearing a crop top and short cotton pants. And she was so perfect, so alluring. I couldn't help myself. I'd fantasized about her for so long... I groped her breasts. She wasn't wearing a bra. I felt up her breasts for what felt like hours. It was only a few minutes. Afterwards, I felt so horrible, I just rolled myself up in blankets and went to sleep. We kept watching Arrow at night though. Few episodes a night. We'd keep the house clean during the day, talk a little, feed the animals and stuff. I'd cook. Only problem with her really is that she can't cook to save her life. But it's okay, I love cooking, and don't mind at all. Next night was the same thing. Couldn't help myself, groping her again. But as it went on, I got greedy. Start of the next week, she wasn't facing me when she was asleep, and I groped her ass. Fuck, it was intoxicating. Firm, but with enough give for it to be interesting. She was in purple trackpants with flannel shirt at this point. I groped her chest again, massaging her breasts lovingly, before I went to sleep again. I'm a horrible human being, but I couldn't help myself. Few nights later, she was wearing the crop top again, with the little pants, and I'd figured out a system by now. She fell asleep after maybe the third episode, (By now we were running out of show, so I suggested Supernatural next. She didn't seem to mind) and after an hour was dead to rights, and I could do pretty much whatever. I was addicted to her feel, her scent. I lifted her crop top that night. She was facing me, and I played with her nipples for the first time, sucking on them a little. She tasted so... mmph, she's addictive. She started to stir though, so I covered her back up and went to sleep. The next day I felt so terrible about it, I feigned sickness for three days. Kept out of the same bed. She seemed a little disappointed, but didn't complain about anything. I thought she might have figured me out, but she just said she liked the company, and that I was funny when I spoke. The next night was too much to bear, and I unbuttoned her flannel shirt, and finally slipped a hand down her trackpants. She was wearing flimsy panties, and I rubbed her through them with one hand, while I played with her tits with the other. Her nipples got hard and she moved. Scared, I stopped again, and went to sleep, trying to deal with my depravity. I didn't sleep much that night. The night after I fingered her. Really fingered her. I slipped my hand under her panties, and rubbed for a little while, watching her carefully, before slipping in a finger. She moaned, and I stopped, but when she didn't wake up... I kept going. I told myself I had to stop, but I couldn't. I thrust my depraved fingers in and out of her sweet honeypot until she orgasmed in her sleep. It was so perfect, the way she sounded under my hands, the way she tasted under my lips (I had started kissing her neck and such as I continued. Her shirt that night was full length. Washing day. Didn't want to risk it) She tasted awesome off my fingers too. She was so embarrassed the next morning, and it was so adorable. I knew I was going to do it again. My dick against her ass was hard the whole time I'd been fingering her, aching for attention. I didn't risk waking her that night by masturbating, but I figured I'd have to next time. But next time was different. I couldn't help it. I had to have her. To claim her. It was the last week of the holidays, and I wanted her so badly. She was in that cute top and pants, and I practically tore it off of her in my lust filled excitement. She didn't wake up. I actually pulled her pants off entirely, and pulled her panties to one side. I played with her cunt a little, licking and rubbing with my fingers to make her ready, and slid myself in her. Fuck, she's so amazing. She gripped me wonderfully, as I slid into her, and out. It wasn't like how they describe it in writing though, it's so much better. Before I knew it, I was hammering her, and she was moaning. When I came, it was inside her beautiful womb, and when I came down from my high, she was awake, and staring at me with half lidded eyes. Terrified, horrified, I tried to pull away, but she wouldn't let me, and she told me she was disappointed in me. I started to panic, and apologized profusely. I was feeling horrible, guilty, disgusting. I'd just fucked my own sister. But she laughed at me and kissed me, hard. She forced her tongue into my mouth for god's sakes, and told me that she was only disappointed it'd taken me so long to fuck her. I was shocked, but she laughed it off, and fucked me again that night, dominant this time. I think I was still in shock. But I have to admit, the rest of that week? Best week ever. The house didn't get much cleaner for a few days, but we did experiment rather extensively. I still liked her sweet, sweet cunt the most, though she did blow me to heaven once or twice. On the last night, we fucked instead of watching a show, and I told her we couldn't keep going, and she said she knew, which was why she'd made this week the best she could. I love my sister, and I might burn in hell for loving her like this. But we still see each other now and then. This was almost two years ago now, when she'd just graduated, and thus turned the legal age as well. Now and then, she'll come over. I've asked her before why she doesn't have a boyfriend, and she told me she didn't need one, because she had me. We fuck whenever we can really, and she visits for quality time too. I visit her as well, but she likes my place better. I had to get this off my chest. Thank you for giving this disgusting, depraved guy that chance.