They never touched.
Even when Suzaku was following Milly's orders and torturing Lelouch with the rest of the student council, they never touched. The… the threat was there, but there was always something that prevented that final contact.
When they were younger, their relationship had revolved around touches. Suzaku was a tactile person and Lelouch had grown up in a loving family until it had been ripped from him. And there was Nunnally, her blindness making touch a necessity for communication as well as a comfort.
Now Suzaku touched Nunnally. He had to. But he never touched Lelouch. And Lelouch never touched him.
At first, Suzaku had been afraid of tainting his friend and Lelouch had become standoffish, offering himself only in small parcels to the world, to anyone besides Nunnally.
Then, when Suzaku realized that Lelouch was Zero. When he finally reached out and touched with a clinical dispassion and honed violence, slamming Lelouch into the ground before his father. Then, Suzaku stayed away out of disgust and revulsion. And Lelouch sensed it, even without his memories.
Even when they became… not quite friends, but no longer enemies… allies. Even then, their touches were abrupt, violent. Suzaku used them to win against Lelouch when words would have only failed him and Lelouch used them to guide and manipulate his Knight. His tool.
Which made their last moment together, as Suzaku shifted so Lelouch's head could rest on his shoulder, as Lelouch lifted his hand to touch the mask as tenderly as he'd never touched Suzaku's face…
That embrace, as Suzaku cried and Lelouch bled, it meant more that it should have. It was years of embraces and tears, compressed into a single moment.
And all without one inch of skin touching.