Bruce Banner stepped back and cast a critical eye over the numerous formulas and equations that covered several whiteboards fixed to the walls of his laboratory at Avengers HQ. He thought back to when he studied similar data in his old lab, way back when he first started his experiments with gamma radiation, and what it had led to.

"The more things change," he muttered to himself. "The more they stay the same."

But things had changed. More than anyone could ever had imagined.

It had been a little over two years since The Avengers had failed to stop Thanos from using the combined power of the Infinity Stones with a snap of his fingers; a simple act that had caused so much devastation. In the time since, civilisation had been rebuilding slowly, but people were still dealing with their grief over those that were gone, and that was just on Earth. Every known inhabited planet in every known galaxy had seen half their population suddenly vanish. Bruce could not even start to calculate the possible number of casualties, solely because of the actions of just one being…

Bruce was snapped out of his thoughts when he heard the door to the lab slide open. He turned to see Natasha Romanoff walk in. He started to greet her and thank for coming like he had asked her to in a recently sent message, but then he saw how exhausted she looked. He could understand why she was tired; he was too. Every remaining Avenger was pretty much on alert 24/7, dealing with the fallout of Thanos' actions globally and beyond; they took time out as and when they could. Bruce used his free time to work on his experiments and research, while Natasha was often away on a personal mission, trying to find someone who was both a rogue operative, and a grief-stricken friend.

"Where did you go?" Bruce asked.

"Back to the Motherland," Natasha replied.

"Russia? Clint was there?"

"Got a lead he was going to hit a Mob meeting in Moscow."

"Guessing it didn't pay off?"

Natasha shook her head. "He'd already been and gone by the time I got there. They were still cleaning everything up when I left, and it wouldn't surprise me if they were still cleaning now."

Bruce chewed his lip. "Any idea where Clint went after that? Where he could be now?"

"None," said Natasha. "And my list of contacts is a little shorter than it once was."

"You'll find him Nat."

"Maybe Bruce," sighed Natasha. "But I'm getting a little scared about what I might find."

She rubbed her eyes to both keep her awake and stop tears from falling. Bruce looked at the floor, not wanting to feel like a voyeur.

"You know Nat, this can wait 'til tomorrow if you…"

"No Bruce, it's OK. I'm OK." Natasha rubbed her face one more time than sat down on a bench near a worktop covered with paperwork. "OK. What did you want to talk to me about?"

Bruce took a deep breath and explained how in the times where he let The Hulk free rather than try and fight for control of his body, he felt he had a degree of control over the monster. He went on to present a theory and plan to expose himself to small controlled doses of gamma radiation over a prolonged period, physically changing his body to The Hulk's, while keeping his own intellect and personality intact. Essentially the best parts of both in one form.

"At least that's the plan," he finished. "My last six months of research reads positive it could work."

Natasha just stared at him.

"Sooooo… is that a good silence or a bad silence?" asked Bruce.

"It's a trying to think of the right words for my questions silence," replied Natasha. "First question being, are you sure this is a good idea?"

Bruce shrugged. "In theory yes. In practice, I'm not sure. If I misjudge the doses, something bad could happen. Again. Now I think I've minimised the chance of anything like that happening, but there is that risk.

"So why risk it?"

"Because the cold fact is, we're struggling Nat. Tony's off the grid with Pepper, Thor's still dealing with missing his shot at Thanos, and Clint is… Clint is anywhere but here. And of everyone's that left, I'm pretty much the weak link of the team."

Natasha shook her head. "C'mon Bruce, you know that's not true."

"It is true though," said Bruce. "Everyone else has powers they can control or is at least trained for actual combat. I mean, there's a talking raccoon who can shoot a gun better than I can. Right now, the Big Guy doesn't want to come out and we don't know if he'll ever come out again, or what he'll be like if he does. I do this, we'll have his strength, and I'll have control of that strength. We could do a lot with that."

Natasha nodded. "All right, next question. Have you told anyone else about this plan?"

"No. You're the first."

"Any reason why?"

Bruce shrugged. "I wanted you to be the first to know."

Natasha took a deep breath. She already had an inkling she already knew the answer to her next question. "It would be a permanent change. You wouldn't be you, as you are right now, ever again, will you?"

"No," said Bruce. "Once I do it, it's done. No turning back."

Natasha nodded again, and forced herself to smile to try and hide her true emotions. To stay in control. "Well, that's a hell of a thing to drop on a girl just like that."

Bruce sat down next to her. "I know it is Nat, and I wish it could be different, but this just seems the best thing for me to do."

"Yeah," said Natasha. "And you're right, it is. That's the real kicker. Having the Big Guy's brawn and your smarts at the same time would be the plus of plusses. From a coldly logical point of view it makes perfect sense."

"Yeah," said Bruce. "Logically."

The two were silent. Bruce watched Natasha as she rubbed her eyes with her right hand again. He tentatively placed his own hand on Natasha's left, who let it sit there.

"I'm sorry Nat," he said.

"I know Bruce," replied Natasha. "Me too."

"Believe me, there's so much I would change if I had the chance."

"You, me and pretty much everyone left on this planet right now," said Natasha. "But we can't change Ultron and everything after that happening, then Thanos happening. We've not even started getting back up from that."

"And it's not just that either," said Bruce. "The Big Guy has always been there and I know you Nat. You go back way too far with Clint to just give up on him. You couldn't stop looking for him even if you wanted to."

She looked at him. "There's just not enough time for everything, is there?"

"No there isn't," said Bruce. "But I really wish there was."

"Me too," said Natasha. "But there isn't. And sometimes, some things just have to give."

The two of them sat quietly, staring at different points of the room but keeping their hands clasped.

"You know," Bruce finally said. "I like to think I would have made you happy."

Natasha smiled and kissed him on the cheek. "To have gotten a good man after all the red in my ledger would have done that."

Bruce offered a thin smile. "You look tired. You should go get some sleep."

"When are you planning to tell the others?"

"I'm going to double check everything again. If it all matches up, first thing tomorrow."

"OK," said Natasha. I'll guess I'll see you tomorrow then."

Natasha offered one last soft smile to Bruce, who squeezed her hand before letting go. Natasha got up and left the lab, leaving Bruce alone to go over his whiteboards one more time.