If you hold someone’s hand over the fire enough times, they’ll learn that it burns.
Tony doesn’t like to be touched because so many, many times people have put their hands on him, it’s been to hurt him. At the age most kids were learning to ride their bikes, Tony was navigating the fine art of reading moods and learning how to duck and run.
He learned that those around him who were supposed to love him, protect him were just as likely to strike out at him. He learned that retaliating just bought it on harder and faster. He learned to roll out of a blow so it didn’t hurt as much, he learned to suffer an arm thrown over his shoulder in silence, no matter how much he despised it being there.
Then he went to Afghanistan.
He learned to fight back.
Intellectually, he knows it’s wrong, that no-one has the right to lay hands on him without his permission but childhood conditioning is a deep scar to heal. However,Tony also learned that letting them see you bleed is a fast road to more pain, so he sucks it up, swallows his fear, shoves his hands in his pockets to hide the shakes and pushes through.
'No' might only have two letters but it's the longest word in the world to try and pronounce when you're under pressure and terrified.