Marty had barely closed his eyes when he heard the door to the cabin open and close followed by footsteps out in the kitchen area.
"Don't worry he's asleep," said Lizzy out in the kitchen to whomever had come to the cabin.
"I'll check on him," said a man's voice--one that Marty recognized and didn't recognize at the same time. A few moments later the door opened and the light switch flicked on in his room. Marty pretended to have been woken up by the light, whimpering and mewing like any infant--which he was now. He could hardly see across the room, objects and shapes at far distances were starting to become fuzzy to his eyesight.
A pair of big strong hands scooped him up and brought him up and close to a face that looked somewhat familiar from last night.
"Well Dad, I bet you have a bunch of questions... so did I when I woke up this morning, which is why I booked it outta here as fast as I could before you two woke up," said the familiar looking man.
"The lake can only make you as young as a newborn if you're not close to a potential mother when you get young enough. In that situation, if your body tries to go any younger it'll steal years off of the nearest other bathers. At least that's what the old doctor told me. So while you've been getting younger all day, I've been getting older--and it's been a wild ride, getting my first gray hairs, getting nose and ear hairs, putting on a few extra pounds, getting called by Mom when you got too young and called "your Dad". It's been one messed up wild ride... and I just wanted to say before you get to being a newborn and we start exchanging years again, it's made me appreciate being a kid more than anything else. You can have being an adult."
This face was Timmy?! Timmy my boy was a man? And not just any man, but my new old man? This was just too freaky to follow. Marty whimpered some more and tried his best to wiggle out of Tim's hold, but his hands were just so big and he was now just so small. Lizzy was Mommy and Timmy was Daddy? What magic made this all possible? It has to stop... Mommy and Daddy... Mommy and Daddy...
"Tim, Marty needs his rest, let me put him down," urged Mommy.
"Uhh... sure thing," said Daddy as he handed me over to Mommy. The moment she held me in her smaller but still big hands, I felt an odd feeling in my tummy.
"It's time to nurse, help me get my top off, Tim," said Mommy. And soon I felt myself being lifted to Mommy's breast where I latched on and began to suckle. However the more I suckled the bigger the breast seemed to get and the harder I had latching on, until the odd feeling from my tummy really started to feel freaky, and I felt something growing from my tummy.
"Pinch the chord Tim!"
Mommy's breast was gone, shapes and colors were starting to blur all together, the thing growing from my tummy was entering something... something wet and narrow and it was connecting to something--and once it did, I no longer had to breathe as I felt at one with Mommy. My feet soon were following the thing from my tummy, stretching the wet and narrow path, followed by my legs, hips, arms and body. Soon it was only my head and with what felt like a pop, I was drug back into Mommy and surrounded by something floating in Mommy.
Tim had watched in horror as his former father was sucked into his former mother, now wife. The old doctor had warned him about getting newborns from the fountain too close to potential mothers, and he'd like an idiot had just handed his Dad--Marty over to Mom--Lizzy, who as soon as held him as unbirthed him. Lizzy now was calming down with breathing exercises from La Maz class that Tim now vaguely recalled--the lake's magic latently adding those memories to his mind. Soon her breaths became spaced out enough that she no longer needed the La Maz breaths, and that's when Tim noticed that unbirthing Marty hadn't stopped him getting younger. Lizzy's belly was shrinking and Tim could only guess what that meant.
"Tim, help me back to bed," said Lizzy, and Tim obliged his now wife and mother to his son... or soon to be son. By the time he'd helped her stand and back into the bedroom her belly had shrunken to a more manageable second trimester.
"It's too bad I'm so big or we could have a little... fun," said Lizzy with a suggestive wink as her belly shrank again.
"That's okay, we don't need to do anything tonight," said Tim, growing nervous as her belly shrank again, now closer to the start of the second trimester instead of the end of it.
"Well, if we're really careful, we can make out... I'll need to be on top though," suggested Lizzy.
"M-Lizzy, I don't think that's a good id--" but Tim never managed to finish that sentence as Lizzy had crossed back into the first trimester and was already locking lips and pulling Tim down onto their bed. Tim at first tried to resist, but soon his own body betrayed him and the memories flooding his brain made his instincts take over as he began to grow desperate for her touch, and she his. All the while her pregnancy ticked away and Marty grew smaller and younger, undeveloping into a fetus, and then an embryo, and then just a single cell as soon as Tim entered Lizzy and they started rocking the bed. Their desire peaked just as Marty's cell split into an egg and sperm, the sperm being sucked backwards out of Lizzy's womb, past the cervix, and into Tim's awaiting and thrusted penis.
Tim felt a shudder down his spine as Marty's sperm found its new home in his balls--though he didn't know it in that moment, but Tim had become his own grandfather.