.superman is not a hero.
The Aizen clan was one of minor nobility -- not especially powerful, but old, and respected, and comfortable. Sousuke was born in Seireitei and had been to the physical world only very occasionally, mostly centuries ago when he was in the academy, and so he was not what one would call up to date on cultural trends. The last he remembered of the physical world, they were developing an intriguing new tool called a locomotive, which Sousuke had always thought might be something they'd want to integrate into the Soul Society to make travel easier; but even then he was more interested in molecular engineering than engineering.
Right before Hinamori was made a lieutenant (thus effectively ending the majority of her missions on Earth) she came to him with her eyes sparkling, and told him about a being called a 'superhero' that they told tales of in the physical world. A 'superhero', it turned out, was even more powerful than a locomotive (but unlike a locomotive, would not be terrible useful in facilitating travel).
One night in the gardens, quite some time later, he was going over this story and considering what she had said; and apparently by accident, Gin happened to wander by, and paused to say with a broad smile, "Nice night, isn't it, Captain Aizen?"
Sousuke responded with a warm smile of his own, and said, "Yes. My evening walks normally aren't so pleasant, but it seems the humidity has lifted."
It was positively banal. Sousuke extended his senses, subtly feeling out the presence of others: they were near the sixth squad offices, and no doubt young Kuchiki had his troops operating like clockwork, the way he liked it. Only low-ranking shinigami were in the vicinity, and all busy with their own tasks.
Gin's footsteps approached him on the polished wood, until the silver-haired captain stood over Sousuke where he sat cross-legged, looking out into the garden. "As I recall, you'd be going out for your walk right about now even if it were raining cats and dogs," Gin observed.
The memory was pleasant, trickled over his mind like cool, soothing water -- a little reminder that here, at least, was someone who knew him. Sousuke removed his glasses and rubbed at his eyes. "A man needs his private moments," he said with amusement.
"Oho? Should I leave you be, then?"
He didn't put his glasses back on. "Do you know," Sousuke mused, "the story of 'Clark Kent'?"
"Beg pardon?" Gin asked politely, still hovering behind him attentively. Anyone else might have been unsettled by the way the already-unsettling Gin loomed over them while they sat at his feet, but Sousuke found it only another pleasant reminder of familiar days.
"Clark Kent is a reporter for a newspaper," Sousuke told him, as Hinamori had told him. "Every day he goes in to work, puts in his hours, plays the pleasant country-boy for his co-workers. But that's not who he truly is."
"Is that so!"
Sousuke smiled. "Indeed. Secretly, Clark Kent is actually called 'Superman'. He has powers far greater than anyone suspects, and a history that no one would believe if he told them. People see Superman on a daily basis and no one ever associates him with Clark Kent. Isn't that funny?"
Gin hopped down into the garden so that he could turn and look Sousuke in the eye, all sober interest without even his sly smile. Sousuke almost smirked, admiring the many earnest masks that Gin could wear. "Now that's an interesting story, Captain! How did this Kent keep everyone from finding out about his secret life?"
"That's the best part," he said smoothly. "No one recognized him because when he is Superman" --Sousuke waved his glasses, smiling-- "Kent doesn't wear glasses and slicks back his hair."
"Ahhh, I see," Gin said sagely. "And that would keep anyone from ever knowing what he was really like."
Sousuke smiled at him. "It's a sad story, don't you think, Gin?"
It was truly impressive, Sousuke thought, how much a very simple disguise could hide; people saw what they wanted to see, after all, and so where they wanted to see a simple reporter or a gentle instructor, they would see that. No one ever needed to look behind the easy smiles.
And it was almost hilarious in the context of Hinamori-kun's story, wherein Sousuke himself had starred as Kent -- gentle and unassuming, and so strong and noble beneath it.
She hadn't even considered her own implication that she might not truly know him.
"A tragedy," Gin agreed, a smirk widening his lips, "being surrounded by fools like that."
Sousuke reached out and settled a hand on Gin's head, an almost parental gesture of approval and affection; one that he would give to Hinamori or Kira without a second thought, and all that he would indulge in here. Gin's hair was fine and soft, stirring and slipping beneath his fingers.
When he moved to replace his glasses, Gin touched a hand lightly to his wrist -- a suggestion, almost a request -- and Sousuke decided to leave them off for perhaps a little while longer.