My name is Dan, I am 18 and I am sharing a room with my sister Ellie who is also 18. We were sharing a room a couple of rooms down from our parents. I made a fake snapchat account and pretended to be a guy called Zack. I knew my step sister was single at the time and was getting back out there. So at 10:30pm I started a general chat, asking where she was from and what she liked. Eventually, the chat went sexual after messaging until 11:00pm.
After a few messages about how hot she was, I sent a picture of the top of my boxers (previously saved pictures as I was sitting meters from her). she replied with saved pictures as well of her bra and thong. I was getting so hard I had to go into the bathroom to reply to her. Once on the toilet, I sent a picture of my dick and she replied with damn that would be the bigger than my exs. I came instantly, straight into the toilet. She then messaged that she would send some pics later in the shower as she was sharing a room with her brother. Once I sat back down, I started to ask her about her brother. She said that he was a year older. I walked back from the bathroom to bed and I asked the dangerous question "Do you have any fantasies?" She opened the message but didn't reply. I thought I'd blown my cover. Eventually, she did reply at 11:26pm. she said, "One time I had a dream that he kicked my ex off me and fucked me himself." This felt like an opportunity.
She got up from her bed and went for a shower and sent a lovely nude picture, waist up, in the mirror. I then asked if her brother had seen her naked. she said "I think he's seen my boobs once, when I came out of the bathroom." Which was true, she had beautiful small tits and now I have a saved picture of them. I tried to get her to flash over snapchat again, but then I heard the bathroom door open. She walked back to her bed and I said I was going to shower now.
While in the shower, I sent her some dick pics, which she liked, and she replied with videos of her fingering herself with her pajamas pulled down. However, in one of the pics I sent, there is a body wash bottle, which she ended up recognising.