He led you to the local park. You spend some time calmly chatting with Billy, but occasional moving of your shrunked brother began to arouse you, so soon you didn't listen what your friend talking.
"Uh, Alice, are you alright?"
"Yeah I'm fine, but I need you right now!" - you said while grabbing his fat rear.
"W-wait, you mean right here?!"
"Well, let's find more fitting place then!" - you lift him and drag into bushes that looks secure enough. - "Okay, here nobody will saw us!"
Billy drop on his knees, while you lift hem of your dress, revealing your panties strained by your already hard cock. He pull down your panties and then notice a bulge in your belly.
"Hey, Alice, what is this?" - Billy placed a hand on your tummy.
"Ah, this... this is... a... breakfast! Yes breakfast, I was very hungry, so ate a little too much... he-he..."
Looks like he believed you, and soon you feel his soft lips around you dick's head. You let him suck you off some time, but you needed more.
"Okay, that's enough! I need your ass, Billy!" - you said as you pull him off. Hearing you he immediately drop on his four, pulling down his shorts, showing you his bare butt and small hard dick. You moved behind him and in one move push yourself into him. That's not your first time with him, so your cock slide inside without much resistance. You began moving your hips quickly picking up pace. Your friend already moaning like a whore and some time later with a loud moan he cums. Usually you make him cum three or more times before you cum, but it seems your sudden moves waken up your brother as he again began thrashing inside, pushing you over the edge.
"Ah, huff... you're pretty quick today..." - said Billy when you finish pumping your loads in his guts. - "W-well, I have to clean myself now, so let's finish our date, I guess..."
When your little sister pushed you into her ass you of course start to panic and struggle to break free, without any success, so you have only hope that eventually she'll let you out. It's warm, wet and dark place and constant squeezing of her muscles start to lull you, though at some moment these squeezings become very intense, but most time you were asleep. Then you feel as the squeezings changed and you start moving and soon you saw the light. Abruptly you're damped into water, you quickly swam toward surface and saw that currently you're in your bath.
"Hello, Willy!" - you saw that Alice is in the bath too, she sat down, creating big(for you) waves on the water. - "How are you?"
"Uh, could be much better..."
"Aww, poor little Willy! Let your sister wash you!"
"Hey, no, no! I-I can wash myself" - you try to object, but without any effect, so you have to survive through bath time with Alice.
After the bath she head to her room, carrying you with her, looks like she's pretty tired from whatever she was doing while you were inside her. She get in her bed and start cuddle you, though you tried to object, again without any success. Your little sister fall asleep pretty quickly, so you had a chance to free yourself from her embrace. Carefully you squeeze yourself out of her hug, at some point she almost wakes up, but you were successful and finally break free. Now, when you're free, you can get back to your quest to grow back. Thinking of it, you remember Alice said that mom taught her, so probably she can help you.
You quietly left Alice's room and head to your mom's. Thankfully her door was slightly open, so you enter without problems. You saw her lying on her bed, she doesn't noticed you yet, looks like she's reading something.
"Hey! Mom!"
"Hm? Oh, it's you Will!" - she look at you and sat down, and you saw that she's completely nude. - "I began to worry, when I didn't found you in your room, but looks like you're alright."
"Mom! I'm not alright! Alice shrunk me down!"
"Well, that's hard to miss... So, you learn her secret..."
"Yes, also she mention that you teach her, so can you help me?"
"Well, I'm not a witch myself, but I can give you advice... I guess you want grow back?"
"Yes, of course!"
"Well in this case you need to drink her cum."
"Ehh... What?!"
"That's not a joke. To revert unwanted changes made by magic you need to drink cum of one that made them."
"But why?"
"I don't know... But, that's how magic works..."