Beauty is blood.
If you ask Kenpachi Zaraki what he thinks is beautiful, you most likely won't get a straight answer. Mainly because asking a man solely devoted to death and destruction, adrenaline and blood and carnage, is like asking a lion why it doesn't see the grace in the gazelle. It's just far too busy ripping the gazelle apart to really give a damn about the elegance of the creature. Beauty to him is something romantic, something superfluous. Something he doesn't need.
But he knows beauty, in its own way. To him it's a nameless thing, lucid and silvery and just out of his grasp, but all around him in any matter. It coats his ragged blade and, if it's a good fight, coats him, too. Whatever he's swinging at is inevitably going to be coated in it as well.
Beauty is the rush of adrenaline following the silver-hot pain of being cut. It's the rush of death breathing down your neck and the weight of your sword stuck in a body, a living, breathing, screaming, swearing thing that's just as ready to kill as you are.
He's not exactly what you'd call 'elegant'. He's far from such a pretty, fanciful word. He's a killing machine by choice. He lives for destruction, and fights for the sake of the fight. There was never really anything else; you fight to survive, that's how it goes in Rukongai, especially in the higher districts. He was one of the ones that just never stopped fighting, like some of the pansies out there that decide once they've gotten a steady income to just stagnate, settle down into complacency. From the very moment he named himself, his life has been bloodshed, a choice that has worked out so far for him.
He's the Captain of a fucking Gotei division. An entire Company of his own. All by swinging his sword at things until they stop moving. This lifestyle's brought him nothing but good so far.
They do call him a monster, and he doesn't contest this. He is a monster; a beast baptized in blood, something that only lives to kill. But no matter how he's lauded as a soulless demon, a devil in human skin, a mindless killing machine, he'll never be mindless, and he's always retained a shred of humanity. This shred, a sliver really, has pink hair and rosy cheeks and happens to be a hyper little killing machine. He doesn't wonder what he'd be like if she wasn't there to link him to humanity, and she doesn't wonder, either. They've never bothered to. There's no point in pondering what isn't real; what matters is what is real, what you do have to worry about. It's not carelessness, just a certain sort of complacency with life that other people hunt for their entire lives and never mind.
It's something Zaraki and Kusajishi both never wonder about. He is content with Yachiru on his shoulder, directing him in the opposite direction he probably needs to go, and she is content in watching over her Kenny, making sure that he enjoys himself. The danger of their escapades is something far away, but always close at hand. The entire division of his is very aware that they could die at any moment. Kenpachi and Yachiru are incredibly aware of their impending deaths, and know that any time they have their fun on the battlefield, that they could come back without the other, without a close friend, or not come back at all.
But this is just another day-to-day thing that they'll deal with. They'll handle death when it comes to them. And it's very easy to say that they'll tackle it, screaming.