"FBI! Put your weapon on the ground!" Rossi shouted, pointing his gun at the unsub.

The unsub was mentally unstable, and experimented on animals, and then humans, trying to find out the secret to immortality.

The BAU had been called in when almost all of his experiments had died.

Elias Green looked at the three agents (Reid, Emily, and Rossi himself) in surprise, his eyes wide.

"Elias, right?" Reid asked after a moment between the unsub and the trio of agents of silence, neither group willing to put down their weapons, "My name is Dr. Spencer Reid. I know..." Reid took a step towards the unsub. Rossi shot Emily a questioning look, she shrugged slightly, "I know what it's like to have your intelligence questioned,"

Green blinked, lowering his knife slightly, "You do?"

"Of course. All of this, this whole time, you've only been trying to help. To better human kind," Green's eyes widened, and he nodded vigorously.

"Yes! Yes! Finally someone who understands!" Reid took another step towards Green, and to Rossi and Prentiss' relief, Green lowered the knife even more, so that it was almost at his side. Rossi lowered his weapon, but Emily kept it trained on the unsub.

"Just give me the knife so you don't hurt someone accidentally. I know that's not what you want to do," Green nodded again, slowly giving the knife to Reid. Emily lowered her gun, reaching for her handcuffs.

Suddenly, faster than Rossi could even register what was happening, Green took something out of his pocket, stabbing Reid in the neck with it.

Idiot! Of course he had another knife!

However, what Reid had been stabbed with was not a knife.

It was a syringe.

"No!" Emily shouted, raising her gun and shooting. Green was hit in the shoulder, dropping the syringe in his hand, and it shattered as it hit the ground.

"Reid, are you okay?" Rossi asked, kneeling next to his younger colleague.

Reid looked at him with confusion. His face seemed to be changing, "Reid?" Rossi asked, taking him by the shoulder and shaking him gently. The shoulder seemed to collapse under Rossi's hands, and he jumped back, looking at the man in surprise.

"Reid!" He shouted. Reid was looking at his hands in horror, as they seemed to be shrinking, then his arms, and his head and torso. Reid cried out in pain.

"What the hell is happening?" Emily yelled.

"It worked." Green said in a smug tone.

"What worked?" Rossi said in an angry tone.

"My serum. It reverses the aging process. And it worked."

Reid let out another cry of pain, closing his eyes.

"Reid, it's okay, Reid, focus on my voice. Can you hear me?" Rossi asked.

Rossi had never really liked Reid that much. He was brilliant, of course, and was a large reason that they solved most of the cases. But even so, he was an annoying little know-it-all, which bothered Rossi to no extent.

There was, of course, the more probable reason why he didn't like Reid, which was he was about the age his son would be if he was still alive. And for some reason, Rossi resented him for this.

But even so, Reid was in pain, and Rossi wanted to do whatever the hell it took to stop that pain that this kid was feeling.

Reid's hair was also changing. It was now a shade or two lighter, and not as curly.

His clothes were now too big for him.

"Is it going to stop?" Emily yelled as Reid let out a child-like scream.

"He would be a newborn, if I had injected him with all of the serum, but I didn't get the chance," Green said as Reid's shrinking slowed, leaving him the size of a two, maybe three, year old.

Reid looked up at Rossi, his eyes shining with tears.

"Uh...Reid?" Rossi asked. The little boy stared at him with large brown eyes.

"He may have lost his memory,"

"May have?" Emily shouted at Green. Little Reid flinched.

"We have a problem, here." Rossi said into his ear piece.

"What is it?" Hotch's voice rang through.

"Well...I think it's something you have to see, Aaron." Rossi said, looking at the small boy who was growing more frightened by his surroundings, "Hey, hey, kiddo, it's okay. You're okay, no one's going to hurt you,"

"There's a kid in there?" Morgan asked over the earpiece.

"Well...sorta," Emily said.

"Sort of?"

"Rossi, he looks like he's about to cry," Emily told the older man.

"I see that, what do you want me to do about it?"

"I don't know, hold him?"

"You're the woman!"

"I'm dealing with him! By the way, we need a medic," She said, nodding at Green.

"Sending one in. We're on our way in, as well," Hotch said.

Little Reid now had tears running down his cheeks, "Hey, it's alright, buddy...Uh...Do you want a hug?" Rossi asked, reaching for the boy and grabbing his arm. The boy didn't respond as Rossi lifted him out of his now too big pants, wrapping the bottom of Reid's sweater around his legs.

"Where's Reid?" Hotch asked as he, the other members of the team, and a medic, entered the room.

"Um...Right here," Rossi motioned towards the boy in his arms, who was looking at Hotch was a terrified expression.

"Yeah...one of his experiments...turned out it worked. And he used it on Reid," Emily explained as Green was handcuffed to the gurney.

"Is...Is this a joke?" Hotch asked. Rossi shook his head, "Let...Here, let me hold him,"

Rossi handed the small boy over, "Here, buddy, I gotcha, you're safe, we gotta take you to the doctor's, 'kay?" Reid snuggled into Hotch's grip.

"JJ's gonna have a cow," Morgan muttered.

"Actually, she's having a boy," Rossi said sarcastically. Morgan shot him an annoyed look.

"How are we going to tell her and Garcia?" Emily asked, "I volunteer Morgan,"

"I agree," Rossi said.

"Hey! Hotch, they're-"

"I have to take him to the hospital. Are any of you coming with?"

"I will," Rossi said. Hotch raised an eyebrow, knowing the relationship that adult Reid and Rossi had, "What? He's grown on me."

"It's been three minutes," Emily pointed out.

"Your point?"

"He just doesn't wanna be around when I tell baby girl," Morgan said.

"You know what? He's grown on me too. I'll come with you to the hospital." Emily said.

"You guys suck. I'll meet you there, I'm probably going to have to pick up JJ and Garcia." Morgan said, taking his phone out of his pocket and exiting the room.

"Reid?" Rossi asked the young boy.

"Spencer?" Hotch asked. The boys head whipped up at his first name. He looked at Hotch, and blinked, "Do you remember who I am?"

Reid gave the man a confused look.

"My name's Hotch, okay? These are my friends Emily and Dave,"

Spencer nodded, snuggling further into Hotch's chest, which was probably hard to do, considering he was wearing a bullet proof vest.

"How did he do that?" Emily muttered.

"It's a dad thing," Hotch said, stroking the small boy's hair.

"I want to hold him," Rossi said suddenly, reaching out for the boy. Hotch nodded, trying to pry the small boy off of him. The boy squealed, struggling to get away from Rossi's hands. Rossi withdrew, a hurt look on his face.

"Spencer, he's not going to hurt you," Hotch told the boy, "He's my friend, you can trust him,"

"It's okay, Aaron, I'm a big boy," Rossi said.

"Dave, he's, like, two, at the most, he doesn't know you, so don't take it personally."

Spencer buried his tiny head in Hotch's chest again.

"I know, and I'm not,"