The humor and lighthearted interaction Bruce was exhibiting was a thinly disguised ruse to keep calm in the face of what he knew was great danger. They were treading on a razor's edge, and though he cared little about his own protection, since the Other Guy had a way of keeping him protected - his concern was for Natalia and completing the mission. If HYDRA was really doing what SHIELD suspected them of doing, then they had to be stopped.
The hall was deserted, thankfully, and he was even more grateful when Natalia managed to pick the lock so they could slip inside. Once in the room, Bruce became tense and he kept glancing around nervously, expecting an agent to appear at any moment. He was glad when Natalia found the paperwork so quickly, and he went immediately to her side when summoned.
Slipping his glasses upon his face, he took the package from her and leafed through the pages, brow furrowed. The information included details of experiments and diagrams, equations and graphs. There were even images, and Bruce froze to see the machine they'd built.
"This is... not good." An understatement. He flipped to the next page and his face fell to read the conclusive statements of their research and experiments. "Not good at all. They've already begun experimenting on human subjects and... shit. They've been successful." He turned back a few pages before to reexamine a portion he had to skim. "I recognize these findings..." his voice trailed off, thoughtfully. They were his own, but mostly Betty's. She'd shown him what she'd been working on the last time they met, years ago... her theories of how Bruce's DNA had been mutated in an attempt to reverse the process and cure him. However, HYDRA was using these theories as a basis to create more monsters, using gamma ray technology. The current thought on Bruce's mind, however was, how the hell did they get a hold of Betty's work?