I came home to an empty house. I knew it would be empty when I got there because my wife, step daughter and mother in law were at a concert and my step son was off visiting this cousin in the next state over, he wasn't coming back until the next day. I figured that it would just be me home alone until the others got back from the concert so I made something to eat and I was just going to chill and watch TV. After about half an hour I hear the door being messed with and when I went to investigate what was going on I found my step son's girlfriend. She had gotten off of work early and didn't want to go home and deal with her family. She seems to spend more time at our house than her own, though I must admit that I didn't know why she came over this time when it was just me there alone. She's a fresh 18 year old whom is 5'7” tall, blonde hair, blue eyes and a thicker girl with a pair of 36 DDD tits. My step son treats her like shit, always yelling at her and calling her names. Personally I don't know why she puts up with him. We sat at the table talking for about an hour and I told her so much about her relationship with my step son. She really didn't answer why she stays with him with the way that she treats her but she did acknowledge that it was bad and she wished that he wouldn't be the way that he is towards her. During our conversation she was stretching and rubbing her neck, I asked her what was wrong and she said that her neck hurt. I the offered to give her a neck rub and she graciously accepted. After about 10 minutes I told her that I was going to go take a shower and if she needs anything she knew where I was. Before I walked off I jokingly said that if she didn't want to be alone that she could join me before I walked off to the bathroom. She didn't say anything. In the bathroom I stripped down and got in the shower, I was in the middle of washing myself when I heard the door creak. I didn't think anything of it as the door doesn't always latch and our dogs regularly push it open to investigate what is going on. After another few minutes I hear the shower curtain open and I see my son's naked gf climbing in the shower. I was kind of shocked and she must've seen it on my face as she stopped and just looked at me for a moment. I then told her to get in, she was letting all the warm air out and she complied. I stood in astonishment for a moment staring at her full figure glistening under the water as it rolled off of her body. Her soft tits hanging. I then handed her her lufa for her to wash herself. When she got done soaping her body down I offered services to was wash her back, she accepted and as she bent down in front of me to put more soap on her lufa she gave me a full view of her tight pussy. Being completely naked there was no way to hide how completely rock hard she made my cock and she noticed the effect she was having on me. As I finished washing her back and started spraying her off she reached around, tightly gripped my cock, and insisted that she repay the massage that I gave her earlier by massaging me. She cot no argument from me as she strokes my cock before dropping to her knees and swallowing my cock down to the base while choking. She then proceeded to give me the best blowjob I've had in a long while before I got her up, bent her over and gave her the fuck of her life. She kept calling me daddy and telling me how good my cock felt in her pussy as I took her from behind while she screamed. When it came time to blow my load I pulled out of her and forced her to her knees. Being the good slut she was the had her mouth open and her tongue out as I blew the biggest load I've blown in years in her mouth and all over her face. I stood there, my cock half limp and she took it in her mouth and sucked every last drop out of me she could get. That was the first time we fucked and we ended up fucking in my bedroom one more time that night before she left to go home. Now any time that we're alone that's what we do and no one else in the family is any the wiser. Che calls me her daddy and she's my good little cum princess. What an arrangement.