Third person point of view: 

"Bruce check the monitors again we haven't seen a possible spotting of Natasha in over three weeks. This isn't right, something's wrong." Tony shouted running into the lab. 

"Do it yourself, I think I'm onto something." Bruce shouted back without looking up from his computer. 

"Ugh fine! J, re-calibrate the computers and open the search up to all across the world again, we can't miss her because we were looking in too small a radius." Tony mumbled while furiously typing. 

"Tony I'm sure she's fine. She probably just changed her hair again, she has a habit of doing that when something bad happens. Now would you stop making so much noise? I'm trying to figure this out!" Bruce screamed as Tony kept typing and started knocking things over. 

"Well at least I'm doing something productive! All you've been doing for the past three months is moping and working on the same problem that can't be solved!" 

"Oh really? I've been doing nothing productive? I'm trying to figure out what happened to Elizabeth so maybe just maybe Natasha will come back! All you've been doing is sitting there chasing a ghost! She isn't going to be found until she wants to be and I am trying to make it so she will want to come back!" Bruce yelled. 

"I'm not chasing a ghost I'm chasing Natasha and now I'm starting to think that you aren't telling me something!" 

"Oh my god Tony! You're paranoid! Can't you see that?"

"Boys!" Pepper screamed from the lab stairs and the both of them stopped staring daggers at each other long enough to stare at her. 

"Don't call us boys. The only person who gets to call us that is Natasha." Tony said angrily.

"Well I get to right now because you are acting like children. Tony, that's enough time in the lab for today, you're coming with me. Bruce I'm not in charge of you, but you should take a break. Go see Bucky or something, he's up in the kitchen, he's making lunch." Pepper instructed and Tony followed her orders immediately and trailed out of the room just behind Pepper. 

"Why did you do that? We were fine." Tony said once they were out of earshot of Bruce. 

"Because. We need to talk." Pepper said coldly while they got into the elevator and rode it to the penthouse. 

"What is there to talk about? I'm looking for Natasha, I'm going to find her, it's just taking me longer than I had expected. I'll have your best friend back to you soon enough." Tony said annoyed as they entered the penthouse. 

"Tony. We need to talk, what's really going on? Please tell me, I'm here for you."

"I'm... I'm fine. I just miss Natasha, that's all." 

"No Tony. When you miss Natasha you act like a moody fifteen year old and act out to try and get her attention. Come on, what's going on?" 

"It's just. I haven't seen anything on the monitors that even come within a twenty percent match of Nat in over three weeks. Before we were getting up to sixty percent matches almost every other day. She has either gone completely dark, gotten captured, or..." Tony trailed off putting his head in his hands. 

"Hey, hey look at me. Look at me." Pepper said guiding Tony's head gently to look at her. "Natasha can take care of herself, she's been gone for longer before and we didn't get anything from her that time either. She is probably fine, she's just being Nat." 

"No, I'm not worried about other people hurting Natasha. I'm worried that she has already killed herself and we weren't there to stop it! We weren't there for her, which is why she did it!" Tony screamed frantic

"Tony, Natasha wouldn't do that. She wouldn't do that without telling anyone, especially Clint and we already know that he's out looking for her right now which is why he went dark two days ago."

"But Pepper what if we missed it. What if we missed her cry for help, because we were too concerned with ourselves to notice it. What if she has been trying to tell us something this entire time and we just aren't listening. You didn't see her how I did! You didn't see how much she hated herself, how much she blamed herself for everything! I have never seen her like that, and what did I do? I ran away! What if she needed me to stay, what if that was her way of asking for help?" Tony screamed. 

"Tony. You can't blame yourself. It isn't your fault, and you did everything you could, you did what you thought was right." 

"What if that wasn't the right thing?"

After Tony and Pepper left the lab Bruce continued to work for a few minutes but he couldn't work without Tony making noise in the background, so he took a break and went to see what Bucky was making for lunch. 

"Hey Bucky." Bruce said when he saw him in the kitchen. 

"Hey Bruce, want some food? I made chicken noodle soup from scratch. It's my moms recipe so don't worry, I couldn't have screwed it up to bad. Don't worry my mom made it for Steve all the time when he was sick, he loves it it's good." Bucky said with a chuckle when he saw the apprehension on Bruce's face as he poured him a bowl. He brought the bowls over and sat down across from Bucky. 

"How was the mission? Did you find anything on Nat?" Bruce asked quietly.

"No, well hardly anything. I found a hotel that she stayed at two weeks ago, but by the time I had got there she was long gone. Clint's looking for her now, it shouldn't be too long before they come parading back in here like nothing ever happened. He'll find her, but I'm not going to stop looking, there's still a few of her old hideouts that I haven't checked yet."

"When are you leaving again? Is Steve going with you this time?"

"No Steve's leading the search parties for her at S.H.I.E.L.D and trying to keep the council from putting out an execution order on Nat. Plus she won't come out if I find her and I have Steve with me." Bucky said with a shrug and the two ate in silence for a few minutes until Bucky awkwardly spoke up. 

"How's it going with the stuff with Elizabeth, have you found anything?"

"I think I maybe on to something, but I thought that the past twelve times and it ended up being nothing."

"Oh." Bucky said and then went back to eating. 

"Actually, do you have any ideas about what might have happened to the baby?"

"Well I'm no scientist, but they did a shit ton of experimenting on Nat back in the Red Room. She went into the med ward for experiments, I don't even know how many times. Do you mind if I came down and looked to see what you had in the lab, maybe I could give you a hand or some ideas?" Bucky asked sheepishly. 

"Yeah of course. Let's finish eating and then go down there, maybe your memory is the key to all of it."

"I wouldn't count on it, my brain is much better than it used to be, but sometimes it still gets jumbled. I would be more than happy to help though, I'd do anything to help make this right." Bucky chuckled and the two shoveled their food into their mouths and made their way down to the lab. 

"OK. So this is what I have here." Bruce said gesturing to the whiteboard on one side of the room. "These are all of the experiments, injuries, and enhancements that I know Natasha has had done to her." Bucky walked over to it and grumbled something in Russian before walking over to it. 

"This isn't enough, this isn't even close to enough. Natasha has had way more things done to her and done to herself than this." He shouted over his shoulder at Bruce who was explaining things that were on a computer screen.

"What? What do you mean this isn't enough. This is more than I have ever seen on one person, especially on the team. She has more than Cap, Clint, you, Tony, me. This is everything that Natasha has told me plus what Jarvis has figured out from the body scan he ran on Natasha."

"Yeah, it's terrible, but it's true. The Red Room captured her when she was probably four, they started experimenting on her then. They did some really fucked up shit in that hell hole. I only met Natasha when she looked about seven maybe eight, but I heard rumors and I'd see her come back with scars."

"Oh my god. I wasn't even prepared for that. Does she even know about it, or does she remember?"

"I don't know. I hope that she doesn't. I know there is certain things she can't remember, I made sure of that. You said her scar tissue ripped which is why Elizabeth died, isn't that a simple explanation. Why do you have all of the ultrasound pictures over there?" Bucky asked trying to change the topic and pointing to the other whiteboard with ultrasound pictures plastered all over it. 

"I'm ninety percent sure that's what caused Elizabeth to die, but I don't know why. Her scar tissue was stable the entire pregnancy. It held up through all of Elizabeth's growth and movement, even when she turned. It doesn't make sense that it would all of a sudden rip while Natasha was in labor, especially because I didn't let her do anything strenuous, well I mean other than being in labor, and why would the scar tissue rip then and not before. It doesn't add up."

"You're right it doesn't. Do you mind if I keep this?" Bucky asked picking up one of the later ultrasound pictures that was on Bruce's desk. "I never got a late pregnancy ultrasound photo and I didn't get a picture with her after she was born because, you know."

"Yeah sure, no problem, I'll print another one off of the computer. What procedures or incidents or experiments did you make sure she couldn't remember, and why did you make sure it was only those, and why didn't you let her remember?" Bruce asked curiosly. 

"Because it's for Natasha's well being and sanity. There's only four of them though. Two were experiments both without anesthetic or sedation when they needed to be."

"OK. What was so special about those, she said she's had a ton of experiment's done to her when she didn't have anesthetic or sedation. She said it was to build her pain tolerance or whatever other bullshit they told her." Bruce said going over to the computer. 

"One is probably more for me than for her. It was when they first started brain washing her, it didn't go well the first time, she screamed all night because of whatever they did to her, I wrote down the date so when they perfected the technique, we could erase certain moments from her mind, I planned on that being one of them. The second one was probably really benign but I tried to make sure that it got erased any way. I'm not sure how much it stuck though, because she started hinting at it to me when Clint was gone. She came back with a pretty big scar on her back and she had started acting really weird after it for about a month and then she went back to her normal self." Bucky said with shame and anger in his voice. 

"Wait a scar on her back!" Bruce exclaimed when Bucky finished. 

"Yeah. It was pretty big, I don't know why she had it either. I asked her but she could never tell me, they didn't tell her, so she couldn't know." Bucky said following Bruce as he started running around the lab. 

"Oh my god! I'm such an idiot! I mean come on you've got seven PhD's Banner and you didn't even think about this! What is wrong with you?" Bruce muttered angrily to himself while running. 

"Woah Banner slow down. You aren't an idiot. What are you talking about?" Bucky said still trying to follow. 

"You wouldn't understand. I can't, I don't have time to explain it. Thank you, you've been amazing now leave, and bring Tony back if you can find him." Bruce shouted, still running. 

Bucky left the lab with an utter look of confusion on his face and looked for Tony for a few minutes before giving up and starting to plan his next mission to look for Natasha. After a little while he went to look for Sam to see if he wanted to train, he always cured his confusion with exercise and Steve wasn't at the tower to go on a run with him. 

"Jarvis! Get me Tony right now!" Bruce screamed with excitement and amazement. 

"Mr. Stark happens to be busy at the moment. Is there anything I can help you with?"

"No I need Tony! I need to show him this! I finally had a breakthrough, get him down here!"

"Mr. Stark is unavailable. Is there anything else I can do for you?" 

"Ugh fine. Get me Natasha's phone numbers, all of them that we know about." Bruce yelled slightly annoyed.

When Bruce got the numbers from Jarvis, he sent an identical text to each of the three phones. 

"I know what happened to Elizabeth. You need to call me now!" Bruce sent the messages and waited to see what or if she would respond. Bruce only had to wait about twenty minutes to get a response from her. 

"Give me five. Make sure we are alone." Natasha responded. 

Bruce put the lab on lockdown and made sure that no one would bother them while they were talking and sat by and waited for the phone to ring. After exactly five minutes the phone rang and Bruce picked up before the first ring ended. 

"Natasha?"

"Yeah Bruce. It's me. Tell me what you know."

"Oh my god. It's so good to hear your voice. We've all been so worried. Where are you? When are you coming home? Do you need someone to come get you?" Bruce asked, almost forgetting why Natasha had called. 

"Bruce, you better not have done this just so you could talk to me because if you did I'm hanging up now!" Natasha shouted furious. 

"No. No. Sorry I just got excited. I miss you. I know what happened to Elizabeth and I know that it wasn't your fault."

"What happened?" Natasha asked from her Paris apartment that overlooked the busy city street. 

"It was the Red Room. It wasn't you and I swear I can prove it."

"Tell me."

"Remember that device that we removed from your back right after the end of the first trimester?"

"Yeah, the thing the Russian implanted in me when me and Pepper went out?" Natasha asked getting out one of her many guns and started cleaning it, she did it when she was she was worried or confused. It was a bad habit she picked up from Bucky. 

"Yes, but no. I went back and I carbon dated it. It was in you for over twenty years. He didn't implant that in you eight months ago, you have had that since you were in the Red Room." Bruce rushed out excitedly. 

"OK. So what does that mean?" Natasha asked still cleaning. 

"It means the Red Room did this to you. All of it. It was their fault not yours."

"OK, you lost me. How did the Red Room do this because of the stupid device thing?" 

"They can send stuff through the device, we know that because they were sending things to help the baby, but that wasn't all they were sending. They were sending neutralizing agents to turn off your serum." 

"Why would they do that? They told me my serum was to keep me safe. Keep me Russia's golden child." Natasha said with anger in her voice.

"Because, your serum is different from everyone else's. It was specifically designed for you, to keep you sterilized, so you couldn't have kids."

"Yeah. I'm still not getting the point Bruce, I still can't see how this is their fault."

"They realized that letting you have kids was more valuable than keeping them from you. They were probably planning to take them from you once you had them. Is what I assume. They turned off your serum with the neutralizing agent for long enough for you to get pregnant and have the kid. Your serum was supposed to attack your womb in case any of it started to heal from the other parts of your serum."

"OK."

"OK. Well they didn't think that we would find the device, and have the balls to take it out while you were pregnant, but we did and it's a good thing too. Remember the day you passed out?"

"Mostly, I can't remember a lot of the details it was a long time ago."

"Yeah that's because they almost overdosed you on the neutralizing agents and it almost completely turned off your serum for forever which would have reeked havoc all over your body and done who knows what to the baby. That's what kept the serum from attacking before, it's what kept the baby alive for so long."

"Why did it all of a sudden decide to attack, and what did it do?" Natasha asked setting the gun parts down on the table and walking over to the window to watch the traffic.

"It started attacking when you went into labor, your body was under stress so it reactivated, the first thing it did was speed up your labor, but when that wasn't enough and it put you under more stress it started attacking your womb and that's how it ripped. That's why you almost died and that's why Elizabeth died. It wasn't your fault."

"It was the Red Room." Natasha whispered darkly. 

"Yeah, Natasha it was. It wasn't you, it was them. If it weren't for them Elizabeth would be alive right now." Bruce said proudly and with a smile. 

"Thank you."

"Of course. Do you want me to tell everyone else or are you going to come back and tell them?" Bruce asked hopefully.

"I'll be back soon enough, I just have to take care of some things first. Don't tell anyone else yet, I'll tell them when I get back, but let Tony know. Tell him I'll be back soon, please?"

"Of course, anything for you Natasha. Anything for family."

"I'll see you soon Bruce." Natasha said with a hint of a smile on her face as she hung up the phone.

"Be safe Natasha." Bruce said after Natasha hung up the phone. Bruce looked up at the ceiling and smiled, he had finally solved the puzzle, he finally got the answer, he finally could go to sleep and tell himself honestly that it wasn't his fault. After a while of smiling like an idiot he fell asleep in the lab. 

After Natasha hung up the phone she smiled. She finally had a reason why everything had happened, she finally had someone other than herself to exact revenge on, she would finally end the Red Room once and for all. She immediately packed her bags and started plotting her revenge with a fury and fire in her heart. She had no doubt in her mind that she would make them pay for what they had done, what they had put her through all those years, what they were still putting her through, they would never be able to resurface again. 

She sent a text message to Bucky after she had laid out all of her plans and found the base that the Red Room had started up again. 

"Russia. 24 hrs. meet me. coordinates enclosed. we are ending those bastards once and for all."

Natasha didn't have to wait long for a response that read. "Understood. I'll be there in 18 hrs."

"Good, because I was only giving you 20." Natasha texted back with a evil grin etched on to her face. After she sent the message she grabbed her bags and made her way to the airport where she would catch a commercial airliner to Russia, she didn't want them to know she was coming. She wanted her homecoming to be a surprise. 

Once Bucky packed his bags, gave the sleeping Steve a kiss on the forehead, and left a note for him telling him he would be back, he sent a text to Clint. "We are taking down the Red Room once and for all. Meet at these coordinates in 19 hrs, if you still want to have a wife." 

Bucky grabbed his bags and made his way to the hangar where he had his pick of jet that he could take. He took a relatively small jet that was mostly used for solo and stealth missions and started the journey across the Atlantic. He left just after two in the morning and the plane told him that he would be in Russia with plenty of time to spare.