A/N: This is written in response to a prompt given by red lighting.
"Based on what I could extract from the archives, I have come up with a method that should work." Max said.
"What aren't you telling us?" J'onn asked.
"In order to reverse the process we need to expose her to the same radiation as when this happened. To do that we need the device that did it." Max explained.
"But we don't have that." Eliza said.
"Hence the problem. Fortunately I am a genius so have a workaround."
"A workaround?" Alex asked unimpressed as she glanced back at Kara who was focused on scribbling on some paper in the corner.
"We have tried it on several rats and got pretty close, eventually. But without the actual device that was used on her I can't guarantee getting her back exactly. Based on the rat experiment I would say we would be lucky to get within five years at the first attempt and whilst we could keep doing this, that didn't work out so well for Roland."
"Who's Roland?" Alex asked.
"My favourite rat, or at least he was until his brain kind of imploded." Max said. "So unless you have found the device we either risk my method or leave her as the drooling, bundle of joy she is now." He said looking at Kara who had grown bored of drawing and was instead attempting to eat the crayon.
"I may be able to help with that." James said entering the room waving a small box in his hand.
"What is it?" Alex asked as she removed the crayon for Kara and picked her up.
"I think it is what caused this. Kara thanked me for a gift I never sent. I think that gift is in this box." He explained handing the box to Max.
"In which case I guess I have a date with Mrs Roland." Max said leaving.
"I'll keep an eye on him." J'onn said following Max out of the room.
Glancing over at Kara and Alex and still being freaked out James said. "I'll go help."
When Eliza, Alex and Kara were alone Eliza immediately picked up on Alex's concern.
"I thought you'd be happy they are close to a solution?"
"I am, but you heard Max, it doesn't always work. Plus we can't really trust him. What if this kills her or damages her?" Alex said putting Kara back on the floor.
"Even if J'onn told you it was perfectly safe you would still have doubts." Eliza said. "You have to go with your instinct." She added as Kara took to flying again. Sensing she wasn't the centre of attention the baby Kara dropped down and picked up two of the foam balls then hovered above Alex and dropped them on her.
"Kara." Alex sighed looking up at her baby sister who was now clapping her hands in delight.
-00-
Three hours later Alex had just managed to get Kara to go to sleep when Max entered the room immediately waking the baby.
"I swear if you haven't found a solution I will kill you." Alex muttered as she picked up her crying sister.
"I have something." Max said. "And trust me I hate children, especially loud crying children. Can't you give her Valium or something? Who knew another of her powers was being super loud?"
"You'd prefer it if she concentrated on her heat vision again?" Alex asked rocking Kara who was beginning to calm.
"No." Max agreed. "Anyway, I'm guessing you don't trust me so here is a tablet with all my findings for you to check and criticise. Something your mother has already done."
"Check or criticise?" Alex asked.
"Both." He said causing Alex to smile. "Anyway we are all set up so whenever you are ready we are."
-00-
"Alex? What happened?" Kara asked looking round not remembering coming to the DEO.
"What do you remember?" Alex asked.
"I went home and then, waking up here." Kara said vaguely. "What happened? You look terrible."
"Babysitting is hard work." Alex said.
"Babysitting?" Kara asked confused. "Whose baby?"
"You really don't remember any of it?" Alex asked.
"Remember what?" Kara asked getting frustrated.
"Miss Danvers." J'onn said entering the lab. "You are back in the realms of adulthood I see."
"Adulthood? Please can someone tell me what happened?"
"You were exposed to a device, which caused your cells and DNA and well you, to anti-age." Alex said.
"What?"
"You changed into a baby." J'onn explained.
"What?" Kara repeated.
"You became a baby." Alex said.
"Have you two hit your heads?" Kara asked.
"We thought you may not believe us so I got a photo." Alex said giving Kara her phone.
"What am I looking at?" Kara asked.
"You. You are that baby."
"No I'm not." Kara said as Eliza entered the lab immediately walking over to Kara and hugging her.
"Sweetie, how are you feeling?"
"Eliza? What are you doing here?"
"Alex needed a little help looking after you."
"Looking after me?" Kara asked.
"When you were...a baby."
"This is nuts. You are all crazy." Kara said. "Why are there halves of table tennis balls covering every corner in here?" Kara asked looking round still confused and seeing that every sharp edge was padded with a half table tennis ball.
"So you didn't hurt yourself on the edges." Alex said.
"Your sister was adamant that the base was baby proofed." J'onn explained. "I just hope we don't have an inspection any time soon. Having bubble wrap covering walls doesn't really convey the right message."
"So you are really saying that I magically turned into a baby?" Kara asked still doubtful of the story.
"Not so much magically." Alex said. "A former prisoner of Fort Rozz did it."
"And then you magically turned me back?" Kara pressed.
"Actually that was more Max." Alex conceded.
"Maxwell Lord?" Kara asked.
"Yeah."
"You know, I think it is more likely that you all suffered from a mass hallucination." Kara said. "People do not just change into babies."
"Perhaps you should show her the video." Eliza suggested.
"What video?" Kara asked.
"We recorded your last hour as a baby. As well as you changing back into an adult." J'onn said.
-00-
"How is that even possible?" Kara asked having watched the video as she finally accepted what everyone had been telling her.
"Well, we don't fully understand the process." Alex admitted. "The worse part is the person who did this is still out there. So it could happen again."
"Great. How long was I like that for?"
"Just a few days."
"A few days?" Kara asked surprised. "I don't remember any of it."
"Probably best that way." Alex said.
"Why? What happened? What did I do?"
"Other than the normal baby stuff?"
"Normal baby stuff?"
"Eating, crying, diapers." Alex listed, the last item causing Kara to pull a face. "Then your powers came out and you flew around uncontrollably. Which you did after stuffing yourself on cookies and as a result you threw up on J'onn's shirt."
"How mad was he?"
"He got over it, I think he viewed it more of a tactical air strike. But it didn't help that the rest of the base kept pointing out that he smelt of baby vomit."
"Baby vomit? That's kind of specific."
"It was a very distinct odour." Alex pointed out. "You also used your heat vision on Max's leg."
"I did? Why? What was he doing?"
"Annoying me."
"Did I hurt him?"
"Not badly, just singed him a bit. He deserved it." Alex assured her seeing Kara was looking a little guilty.
"Where did all the toys come from?" Kara asked.
"Winn."
"Winn saw me as a baby?"
"He did."
"And James?"
"Yeah."
"I can never see them again."
"It's not that bad." Alex said.
"Yeah it is, I mean neither of them are here now."
"Right, well Winn thought you might be a little freaked out so wanted you to have some space. James is kinda freaked out, but he did find the device that did it to you that allowed Max to reverse it."
"But he is still freaked out?" Kara asked.
"Just a little." Alex confirmed.
"What about Cat? Did I miss work? Am I fired?"
"Relax mom went to see her and filled her in."
"She did?" Kara asked confused.
"She also took the opportunity to criticise Cat over her treatment of you."
"What?" Kara asked paling. "Why? How? I am so fired."
"Relax, I'm just kidding." Alex said. "The first two days were the weekend and then Cat got called to a meeting in Metropolis so didn't notice your absence."
"So Eliza hasn't seen Cat?"
"No."
"That was mean." Kara complained.
"But funny." Alex smiled. "Besides what you've put me through these last few days I get a free pass for awhile."
"What did I do to you? Did I hurt you?" Kara asked immediately worried.
"No. You just got a little possessive and didn't like me leaving your sight. So I have been babysitting you 24-7 since it happened."
"What about when I slept?"
"Once your super hearing set in you couldn't sleep."
"I guess that explains why I'm tired."
"Why you're tired?" Alex asked not even sure how she was still standing let alone explaining things to Kara.
"And hungry." Kara added. "I'm going to get something to eat. You want anything?"
"No." Alex said shaking her head as she watched Kara go before collapsing into her seat and shutting her eyes. When her lab door opened a minute later she wearily said.
"Don't make yourself sick from eating too fast."
"I wasn't planning to." Eliza said.
"Mom?" Alex asked opening her eyes. "I thought you were Kara."
"I guessed. How is she?"
"Tired and hungry apparently." Alex said.
"So fifty percent normal?" Eliza smiled. "How are you?"
"Tired." Alex confessed before asking. "Was I that much trouble?"
"I think all children require effort." Eliza smiled. "But you did great with Kara. You were a real natural."
"Oh, no, don't even go there." Alex said.
"Go where?" Eliza asked innocently.
"I know that look."
"What look?"
"The look where you are planning out my life. And to make this clear if this has taught me anything it is that me and kids aren't happening."
"I used to say the same thing." Eliza pointed out. "But having you was the best thing to ever happen."
"Well don't get your hopes up I have no plans and zero desire for kids." Alex warned. "Besides looking after Kara, baby or adult version, is a full time role."
"Hey." Kara protested walking in and catching the tail end of the conversation.
"It's true." Alex shrugged before explaining. "I was just explaining to mom why her delusions of grandchildren are staying delusions."
"You suggested Alex should have kids?" Kara asked Eliza.
"I just said she was a natural looking after you and would be a great mother. And that she shouldn't rule out having kids."
"That's nuts." Kara said.
"Thank you." Alex replied grateful for the help, right up until Kara said.
"I mean you would need a boyfriend first. And let's face it your track record is not great."
"She's right, you should really get out more." Eliza said. "Besides, you are not getting any younger and your biological clock is finite."
"That's it. I'm going where there are no crazy people." Alex said throwing her arms up in frustration and leaving her lab, leaving the amused other Danvers to smile at each other.
-00-
Alex lay down on her bed looking forward to a night of uninterrupted sleep. Closing her eyes she allowed sleep to engulf her. But minutes after she dozed off a loud knocking woke her with a start. Sitting up she listened wondering if the knocking had been in her dream. Having convinced herself the knocking was real she stumbled out of bed and went to her front door. When she opened it she saw Kara on the other side.
"Sorry did I wake you?" Kara asked.
"It's been kinda your thing over the last few days." Alex said as she moved away from the door.
"Sorry." Kara apologised again. "I was worried, you disappeared from the DEO."
"So I could get some sleep and not have mom go on about kids."
"You weren't answering your phone."
"I turned it off." Alex explained before repeating. "So I could get some sleep and not have mom go on about kids."
"Sorry. I promise I will no longer suggest to Eliza that you need a life or encourage her about your offspring."
"Good." Alex said turning away from Kara and heading to her bed.
"But that doesn't mean I won't remind you." Kara warned.
"Of course not." Alex said as she collapsed on her bed.
"Um Alex?" Kara asked following Alex to her bedroom.
"Yeah?" Alex wearily said, her voice mumbled from talking into her pillow.
"Do you mind if I stay? I don't want to be alone."
In response Alex rolled over to one side to make room for Kara who immediately lay on the bed next to Alex and hugged her.
"Thanks." She whispered.
"S'ok." Alex mumbled.
"Thank you for everything." She said hugging her tighter.
"You're welcome." Alex said before adding. "Now please go to sleep."
-TBC...
A/N: Thanks to red lighting for the prompt and Frozenfever9712 for the advice. I hope you have enjoyed it. Thanks for the reviews - those who I couldn't respond to I did appreciate the feedback.