If he was anyone else? Yeah, it probably would have fried his brain. But as it stood, it was more like a hard reset. The Hollow goes unconscious as the two share power; human, shinigami, and hollow blending back into more or less equal amounts before splitting back up again.

It was the power that turned Shiro back on again, gold-on-black eyes shooting open once more as his pounding headache persisted. He rolls over onto his back and holds his forehead, but the majority of the pain is gone as quickly as it had come. And in it's place, that familiar burning of raw power in his chest. The power to level cities, to destroy anything, to rip holes in the fabric of space itself. The power he was used to, so used to, that he needed it to function.

He paws at his eyes and then looks at Ichigo.

"... Phew. I wasn't expectin' that."