A/N McBaby is back! This is for everyone who wished Tim could remain a baby and be forced to relive his childhood. Just so everyone knows there will be some time jumps to move the story along. Big thanks to my awesome beta, Gotta! I hope you enjoy!

PROLOGUE

It had been two and a half weeks since Tim's initial descent into an enforced second childhood. After the first week, they'd hoped the drug would wear off as with all of Lucy Grey's other victims, but as they approached the end of the second week they were preparing themselves for the strong possibility that he wasn't going to change back. Rightfully so, Tim was still in denial over the fact that he would be forced to relive his childhood. Every few days he would ask Gibbs if he knew when he was going to turn back. Those were the days that broke Gibbs' heart the most. He was getting good at reading Tim's facial expressions so when he scrunched up his nose and got an inquisitive look in his big green eyes, Gibbs knew the question was coming. Each time he answered, tears would well up in Tim's eyes and his bottom lip would stick out in a pout. It usually ended with Gibbs pulling the baby into his arms and comforting him until he cried himself to sleep. Then there had been other days where Gibbs' sweet little boy would test his patience to the extreme.

Unable to fully express the emotions he was dealing with; Tim would often lash out, throw a tantrum or defy Gibbs. And while Gibbs would try to comfort and reassure him that he would always love and be there for him, the little guy was still having a hard time. It wasn't until the end of his second week as a toddler that Gibbs started noticing minor changes taking place regarding Tim's mental capacity. Throughout his regression, Tim had maintained his adult mind, but it appeared that was diminishing. When Gibbs would ask him a question about email or work it often took Tim more time to come up with an answer than it normally would. Ducky seemed to think it was because of Tim's unsettled emotional state but the churning in Gibbs' gut was alerting him it was something different.

He had been out on leave while they waited to see if Tim would eventually return to adulthood. Although DiNozzo took point at crime scenes, Gibbs still oversaw their reports and was kept in the loop. It had become routine for the two of them to sit at the kitchen table and read through case reports together. It made Tim feel as if he wasn't missing out on everything as well as keeping his sanity. Unfortunately, one morning, Gibbs was heartbroken but not surprised to see his premonition come true.

Shoveling the last spoonful of oatmeal into Tim's mouth, Gibbs wiped his face with the bib and handed him a bottle of milk. Tim's dexterity was improving and he was now able to hold the bottle on his own. After clearing the breakfast dishes and pouring a fresh cup of coffee, Gibbs powered up the laptop and sat down.

He glanced over at Tim who had his eyes closed and was sucking contentedly on the bottle. Rubbing his hand gently over the back of Tim's head, he asked, "Ready to do some work, Timmy?"

Slowly opening his eyes, Tim shrugged his shoulders and gave him a confused look. Trying to ignore the feeling in the pit of his stomach, he collected Tim in his arms and sat him on his lap. Opening the laptop he kissed the top of Tim's head, "Let's see what awaits us today."

Snuggling back against Gibbs' chest, Tim continued to suck on the bottle as the older man opened his email and pulled up the folder of case reports that needed to be signed off on. Once he got the first report pulled up he watched for Tim's reaction. Instead of scooting closer to the computer so he could read, Tim was content to stay where he was.

More concerned that this wasn't the Timmy he knew, Gibbs laid his hand upon Tim's forehead to check for a fever. Satisfied he was not running a temperature he adjusted the toddler in his lap so he could see his face, "Timmy, You always like to read the case reports, what's wrong?"

Tim popped the bottle out of his mouth and once again shrugged his shoulders. "Me no no dada."

"You no, no, what Timmy? You don't feel like reading the reports today?"

Following another puzzled look from his little boy, Gibbs was beginning to worry. The baby relaxing in his lap was not the same one who was overjoyed when they read through reports a few days ago. It appeared Tim had no idea as to what he was referring to and didn't care either. Yes, there was definitely something wrong and he needed to find out what that was. Trying not to panic, he decided it would be easier to ask him something his adult mind would know, but a toddler wouldn't. Stroking Tim's cheek to get his attention, he waited until he looked up at him.

"Tim, do you know what nine plus four equals?"

The youngster's brow furrowed and he shook his head. "Wha dada talkin bout?" Tim thought as the older man stared at him as if he had just seen a ghost.

Feeling his heart rate increase and the room start to spin, Gibbs had to remind himself to breathe. Following a few deep breaths he looked down to see Tim studying him intently. It was now evident to him that the regression drug was still wreaking havoc on Tim's body and that his mind had regressed and taken the vast majority of knowledge with it. Of course he wouldn't know for certain the severity until Ducky weighed in with his opinion but it appeared Tim now had a mind that matched his body.

A million thoughts ran through his mind; including the loss of his youngest agent and member of his team to making sure he was able to adopt the little fella'. Tim didn't have a great childhood or know what it was like to have a father in his life. If there were one thing Gibbs was determined to change that would be it. Everyday he would tell Tim that he loved him, was proud of him and he should follow his own dreams and not anyone else's. Heartbroken that Tim would have to relearn everything he shut the laptop, leaned back in the chair and pulled his baby close.