Sound
He had highly developed senses. He was Tony Stark, he had highly developed basically everything. Sight, he sorely needed. To build new things, for missions with the suit, without his eyes he'd be dead. And of course to admire her, her beautiful golden red hair, her sea blue eyes, her long legs.
Touch, he claimed to be his favourite. Working with small tools, holding the steering wheel of fast, fast cars, stroking soft skin.
But his real favourite was hearing. His music he loved, her laugh he needed. Without her voice he'd have died in a cave in Afghanistan. He had that first fateful day they met decided that her laugh was his favourite sound in the whole world.
But now, sitting in the doctor's office, listening to the sound from some small machine (he could probably build a much better one, more efficient) he changed his mind. This sound, this one small wonderful sound, was the most perfect sound in the world, even better than her laugh, or her small sobs as she clutched his hand.
The sound of the heartbeats of his children, rapid and soft and scary and so, so significant for that bit of noise. Sound may be underrated, but it was his favourite sense. Ever.
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