So this idea owes . . . most of its existence to notbug, who told me of the inside joke that inspired Orochimaru's question, and Lulubelle, who joined in on the conversation.
I was so tickled by the thought and my initial impulse regarding it that I simply had to write.
Tsunade straightened from her stretch and tipped her head to look up at Orochimaru when she realised he was just lingering at her side after approaching. His sharp eyes skimmed her up and down quickly, then met her own once more.
"I have a question." Orochimaru said, not unexpectedly given both how he seemed to be waiting and his expression.
"I appreciate questions." Tsunade said dryly - and not entirely honestly, perhaps, but Orochimaru's questions were often interesting.
"Your chakra flow pattern," Orochimaru began, and Tsunade focused, curious, "it is stronger in places it once was unremarkable. And there is seemingly static chakra built up outside of your core. Are you storing chakra reserves in your breasts?"
Tsunade froze. She glanced down at her own cleavage before she could stop herself, and then back up to Orochimaru's wide golden eyes, bright and inquisitive and entirely serious and she- she couldn't help it.
Tsunade choked on her laughter. "Am- Am I- storing chakra reserves?" she repeated through hitching attempts to breathe. "In- In my breasts?"
"Tsunade?" Orochimaru said, a confused lilt in his tone.
It only made things worse. Tsunade grabbed onto his shoulder for support, to keep her face - and her breasts; she cackled a little louder - out of the dirt as she doubled over, unsteady on her feet, gasping for breath between gales of laughter.
"You have a high concentration of chakra there, unmoving even." Orochimaru said, though he wound a hand beneath her free arm to support her. "Why else would so much chakra be in your breasts?"
It was good Orochimaru had offered additional bolstering, because Tsunade couldn't breathe for laughing and her legs nearly gave out. It took her another few moments but she managed to catch her breath and straighten, only the occasional giggle escaping her.
Orochimaru was waiting, meeting her eyes again with a puzzled look.
Tsunade giggled again and then forced it down. "No, no." she said, patting him absently. "I understand."
"For fuck's sake, and I can't get away with saying anything around you, but that's fine?" Jiraiya demanded stridently from where he'd been 'meditating', and Tsunade shot him a rude gesture without looking. They all knew why Jiraiya could get away with nothing, and in fact Orochimaru looked faintly offended now as he drew in on himself. Jiraiya muttered, a little too low to hear from this range, but probably further complaints. Tsunade ignored him.
"It's a chakra channelling trick." Tsunade told Orochimaru, snagging him by the elbow before he could pull back. "It offers support," she explained, gesturing at her chest with her free hand, "otherwise these . . . get painful." Orochimaru blinked. "Weight, balance, they're basically fatty tissue with no muscle there, it's very uncomfortable. Especially when moving rapidly or with sudden shifts in direction. And gravity."
Orochimaru still looked faintly confused, but he nodded, dropping his gaze to her chest in a considering fashion. Coming from anyone else the eyeline and the expression would have demanded correction in the form of punching, but Tsunade was well aware of how Orochimaru's brain worked by now and she just shifted and waited. Jiraiya's muttering got pointedly louder, and she glanced at him, narrowing her eyes. Jiraiya made a face at her in return. But he did shut up.
"It's just a channelling trick that essentially goes nowhere," Tsunade offered, returning her attention to Orochimaru with a roll of her eyes, "call it," she snickered, "structural integrity. Can you sense how it works?" she asked, curious now herself. Orochimaru shook his head, frowning slightly as his eyes narrowed.
Orochimaru met her gaze again and raised one hand slightly, and Tsunade hesitated, but only for half a breath before she nodded permission.
Orochimaru's fingertips settled delicately on her ribs, two of them resting on the breastband that did almost nothing to offer support - it had worked fine for her for a time, but . . . no longer - and narrowed his eyes again, looking intently at her chest. Tsunade stifled another burble of laughter, because from no one else would she tolerate this, but-
She stilled; she could feel Orochimaru's chakra - sharp and with an almost slick feeling - delicately phasing through against her own. She shivered as it slipped a little deeper, but they had - all three of their team - shared and meshed chakra enough that the foreign sensation was . . . strange, yes, but not uncomfortable, and easy to accept.
"I see." Orochimaru murmured, pulling back, fingers trailing down her side as they dropped away. "A fascinating use of chakra," he arched an eyebrow as he looked her in the face again, "the coupling of the closed circuit through your body providing," his lips twitched, "structural integrity. Not something I would have considered." he added.
"There's nothing extra anywhere on you to need that much support," Tsunade pointed out dryly, "in fact I'm still not sure you have any fat on you - healthy fat included," she scowled and crossed her arms, "do I have to go back to dragging you to meals to be sure you eat enough?"
"I am not a child," Orochimaru said, but his lips quirked upwards at one corner, "I am quite capable of feeding myself."
"I'll believe that when I see it, you bony thing." Tsunade prodded him pointedly right inside the arch of one of his entirely too thin hips. He eeled away smoothly, a playful light gleaming in his eyes as he ducked an instant before she let fly with an equally playful punch at his face.