It had been a month since the night Milhouse had toyed with Bart in his sleep and Lisa awaked. Since then, he had not had the opportunity to have sex again, with them or anyone else, even though Bart had slept at his house only a week ago. Milhouse had to resort to hand, but it was getting tiresome. After having a feel of both Simpson kids, he craved for more. Bart had quickly forgotten his strange wake of a month ago, but Lisa hadn’t. She had remained somewhat distant of him however. The sex had been good, but she was only interested in playing with Milhouse, not actually dating him. But even from afar, she could tell Milhouse wasn’t only interested in her. She noticed the glances he gave her brother’s butt and crotch area, even though Bart didn’t. Maybe she could do them both. Everyday of summer seemed the same for Bart. Not that it was a bad thing. He liked to spend his days roaming around Springfield, with his trusty sidekick Milhouse at his side. Playing video games, blowing stuff up, watching Itchy and Scratchy… it was the good life. Milhouse had been invited to stay for the night at the Simpsons, again. This time, Homer and Marge would be gone until late into the evening however. Lisa had managed to convince her dad that they deserved a vacation and that she could baby-sit Bart. “I’ll let him invite Milhouse,” she added. “It should calm him down for the night and I’ll be able study in peace.” The first time Lisa had babysat Bart, it had turned out to be a disaster, but somehow, the people of Springfield had forgotten, her parents included. If his best friend could come stay the night, she didn’t expect trouble to arise. And anyways, she had other plans for the night then sleep. So, after Marge cooked a meal for her kids, she left for an evening of fancy restaurant and dance. Maggie was even brought to Patty and Selma’s, so Lisa would have less to worry about. Milhouse arrived shortly after the parents’ departure and immediately, he started playing video games with Bart. Lisa had planned out the evening perfectly. She knew exactly how to act to manipulate Bart to do it with her and Milhouse would surely follow. It would be harder however to make him perform with Milhouse, something she really wanted to see. Bart however, had plans of his own. He knew he wasn’t the smartest, especially in front of Lisa and even Milhouse. He did have one thing he could use to his advantage however: he was cunning. Everyone knew Milhouse had a crush on Lisa and Bart had to admit that even him could see her sexiness. Tonight was perfect to set his plan in motion. The boys played video games for about an hour. Even though Bart was the better player, he was beaten more then once by Milhouse since his mind was elsewhere, preparing to set his plan in motion. Lisa was in the living room, with headphones, seemingly lost in a novel but also pondering her plan. After Bart’s final defeat, he decided he didn’t want to play video games anymore. He decided to bring Milhouse to his room . ‘Perfect,’ Lisa thought, ‘it’ll give me a chance to prepare my plan.’ “Ok, Milhouse, here’s the plan,” Bart said after closing the door to his room. “You like my sister a lot. Tonight, I’m giving you the opportunity to have sex with her.” “But Bart, I already did have sex with her.” Bart, who had been walking towards his bed, stopped in his tracks and slowly turned to Milhouse. “You did?” “Yeah, when I slept here a month ago. She caught me peeking at your parents having sex and since we were both turned on, we… well, she decided to have a go at it. Still not going out though. One day Lisa, one day.” But Bart had not listened. This was perfect. Since Lisa had prior contact with Milhouse, he could make his plan go even smoother. “I’m guessing you would want to do it again.” “Of course! Any time!” And he mentally added: ‘I’d like to slip inside your butt again too, Bart. Ten minutes later, Lisa was ready to start her plan. She walked up to her brother’s room and was surprised to find the door closed. As she was about to knock, Lisa decided just barge in and surprise them. She suddenly opened the door, but recoiled slightly from the sight before her. On the bed, Bart and Milhouse were both kneeling, nude and legs spread, revealing two small but hard weeners. “Bart! What are you doing? Put some clothes on!” Lisa shouted, forgetting that she was going to make him do the same thing an instant earlier. “Aw come on Lisa, you know you want some of this,” her brother said, thrusting his hips in her direction while talking. “Besides, Milhouse said you already did it.” The blue haired boy looked away, a bit ashamed of admitting it in front of her. “What? You little… I…” the girl stuttered. “He screwed you while you were asleep Bart! Did you know that?” Actually, even she didn’t know it, but a wild guess might turn the situation around. Anyways, she already know Milhouse was hot for her brother.