If Deidara was honest with himself, which he wasn't often as honesty was sometimes uncomfortable, what really drew him to his touchy partner were his idiotic views on what was truly ART.
He'd not been at all interested in the hunched form of Sasori until he'd learned from Kisame that it was called Hiruko, and that Sasori had made it himself. Sculpted it himself. Painted it himself. Dreamt it up himself. Given it that silly handkerchief himself. Made its eyes move independently of each other, himself. He'd dismissed it as a strange affectation, similar to his clay birds that were big enough to fly him wherever he wanted to go.
Deidara had been curious, but not overly so, when Sasori himself had banged out of Hiruko in a huff at something rattling one day. Some part of him had known that there was something in there, after all. He'd taken in the petit form and the delicate lines with a single glance and dismissed his surprise that such a deep and gravely voice could belong to someone that looked no older than he did. He'd watched Sasori march around the puppet until Sasori had taken off part of his arm and tightened something, he'd realised that this Sasori too, was a puppet.
After this particular revelation, he paid particular attention to Sasori's eyelashes; the way each one looked perfectly natural and idly wondered whether Sasori ever had to replace them. How long it would take him if he did, both to notice and to change them? Where on earth would he get them from? Did he have to put them in singly? What was the point if they were just going to fall out again?
He noticed how Sasori's head occasionally rattled loose if he chased him down a long flight of stairs and how after a month trekking across the Suna deserts, Sasori's joints had been worn smooth enough to slip and throw him off-balance. Sand wore down wood, so what was the use of Sasori's art form if it was not as immortal as he liked to claim?
There was nothing fleeting, or beautiful about Sasori's art. All it did was slowly decay until Sasori noticed and replaced it with something new. But even that died in the end. What if one day the sand got into the heart cannister? Could he replace that, or would the cycle come to an end? The beauty of Deidara's art was that it was gone, swallowed up in a blaze of light before Time managed to entwine her grubby tendrils around something that belonged only to him.
Deidara's innate curiosity would get him killed one day. It was one of Sasori's favourite sayings, usually applied when the younger nin had tried to blow up something unwise, but it was this curiosity that drove him back to Sasori, to take his life in his hands when he criticised Sasori's art. Or tried to blow Sasori's puppets up that strayed near enough, of course, if Sasori wouldn't make his art beautiful, then Deidara would happily do it for him.
Deidara had spent years watching Sasori craft his puppets, seen the endless hours that went into the finished item and wondered privately to himself if Sasori's reluctance to destroy his creations, was because he didn't want to be continuously making new puppets. Wood was a much more difficult medium than clay; it had its own grain and imperfections whilst clay was smooth and easily moulded into streamlined masterpieces.
Wood lasted longer in sandstorms however. Sasori was never going to let him forget that. The smug git. This was why introspective ponderings were not Deidra's favourite way to spend an idle hour or so. Sasori always ended up winning, in some obscure way.