Biff's heart fluttered when he opened the door to see Sarah standing there. She was looking great in a short skirt and tight top which showed her boobs in all their glory. He wished more than anything that she'd recognize him for who he really was but he knew that wasn't going to happen. He felt instant attraction to her but it manifested in a very different way. His nipples started to become erect and he felt the muscles inside his vagina twitch ever so slightly. He regained control of himself and welcomed her in. Sarah complimented his outfit and he felt a strange sense of pride. Jon had stayed upstairs. He was a little worried about being seen by Sarah, dressed as he was. He was also a bit nervous about being left alone with her and being away from Biff for so long. How would he communicate with her? He needn't have worried as in the new setup Sarah was his regular babysitter and was well tuned in to all the needs of a two year old.
Biff told her Jon was still upstairs. He shouted his goodbyes to Jon, not wanting to delay any further and grabbed a purse and coat which he carried out to his car. Biff opened the door of the car and being careful in his dress sat in the drivers seat and then turned to bring his legs in. He closed the door, took a deep breath and then backed out of the driveway. The plan was for him to drive to Laura's and leave his car there. They would then get a taxi downtown for their night out.
Sarah closed the door as Biff was backing out the driveway and in a playful tone called up to Jon. She didn't wait for him to come down, instead she bounded up the stairs and into Jon's room where she found him looking sheepish standing by his bed. She got straight into it, giving Jon her undivided attention and crouching down to his level. When she did, Jon saw straight up Sarah's skirt at the pink panties she was wearing underneath. He felt his penis twitch slightly within his diaper and embarrassingly he also felt a stream of pee escape. Sarah asked Jon what he'd like to do. She gave him the options of playing a game in his room or maybe going downstairs to watch a cartoon. Jon was so nervous that he continued to pee in his diaper and soon it was soaked. He tried unsuccessfully to stop himself but he couldn't get the hang of it. Sarah sensed his discomfort and since he hadn't really responded to her suggestions decided to make the decision for him. She said to Jon in a very soft, reassuring voice, "C'mon sweety, let's get that diaper changed and then we can go downstairs and watch some cartoons." Jon couldn't believe it, Sarah McMillan, one of the hottest girls from his school was about to change his diaper. He didn't have time to object before Sarah scooped him up easily and placed him down on his changing table. She hiked his dress up a little bit and unfastened the diaper to open it. Jon was going through a huge amount of emotions all at the same time. When Sarah pulled the diaper away from Jon's crotch and the cold air hit him both he and Sarah were surprised when another stream of pee shot out of him and hit Sarah, leaving a big wet patch on her top. Jon could only imagine how Sarah would have reacted in the past but now, since she saw him as a cute baby, she just laughed it off and with a laugh said, "ewww. Gross. Well, accidents happen, don't they. I definitely need to change my top. Maybe I can borrow one of your mommies tops Jon? We're roughly the same size." As she said that last part she gingerly peeled her own top up and over her head, being careful not to touch the pee stain on it. She scrunched her top up and left it down. She'd deal with that later. She now stood beside Jon in just her bra. Jon felt his arousal picking up but he was thankful it didn't manifest physically. He just stared open mouthed at Sarah. He said to himself, "I can't believe I'm looking at Sarah's boobies up close like this." He hadn't meant to say it out loud but all Sarah could understand was, "Sarah...Boobies..." and a few other sounds that made no sense. She blushed but didn't cover herself up. Instead she just said to Jon, "That's right sweetie, these are my boobies and when you grow into a big girl you'll have a pair of your own too, just like me and your Mommy!"
Not wanting a repeat accident Sarah, still in just her bra, grabbed a clean diaper and slid it under Jon's legs. She wiped his crotch with some baby wipes, not paying any notice of the penis he still had. She closed up the diaper, which Jon was thankful for as his penis was starting to grow erect from all the attention, although he doubted Sarah would even notice it. She fixed his dress back into position and set him back down on the ground. Jon followed Sarah as she headed into Biff's room to try to find a top she could borrow. She had a look through his dresser. She pulled out the men's t shirt that Biff had bought the day before, a little bit curious about why that was in there or who it belonged to but she soon moved on. Eventually she found a top she could wear. Jon had been sitting on the bed watching her and he was a little sad to see her pulling the top on and covering her boobs that he had so enjoyed looking at.
Sarah picked Jon up and was chatting away to him in a babyish voice as she carried him downstairs. She set him up with a cartoon and grabbed a bottle of milk from the fridge. She sat herself down on the couch and started using her phone, not paying much attention to Jon for now. Jon sat down and was suckling on the bottle and mindlessly watching the cartoon. He was getting over his anxiety about Biff leaving and was starting to relax. He knew Sarah would take good care of him.
