The first real feeling she remember is fear.
It's also the moment where it became she, not everyone begins as a living being.
It was in Siberia, and FRIDAY remember vividly the moment where she lost her connection to the boss' armor. She had immediately contacted The Vision, relayed every info she had about the base and the damage both on the suit and the boss, those she had recorded anyway.
The Vision had organised the rescue, she...
She was still afraid, too frightened to act.
He stayed with her, calmed her down, and made her promise to keep her fear secret ; organics being don't like when synthetics think and feel.
Only Tony could know, he would know anyway, he knew her code, he made her, he would notice.
She was afraid again, not for him, but of him, would he erase her ? Destroy her to prevent any possibility of a new Ultron ?
He didn't, he just laughed when she first told him that she had been worried, then he had been afraid as well, knowing that her new sense of self had to stay secret.
He began to call her "his girl" in public, which was just a step away from calling her "daughter", but better seem like an eccentric genius than a dangerous one.
When Captain Rogers came back, Tony stopped being Iron Man, he was getting too old, his chest had never recovered from the shrapnel, then the ark reactor, then the shield...
The Avengers never crossed path with Tony Stark, she made certain of it.
For a while everything was alright, the boss still missed flying, but his work kept him busy. Plus, he had another more special project...
Then the aliens came, an ugly purple guy named Thanos, they won, with Tony's help, they won, and she was afraid for her father once again.
She couldn't follow him in the asgardian palace, couldn't make sure they would truly heal him.
She began to work, the old bots that assembled the armors were still there, she just had to give them a push and a new design to follow.
When the avengers came back, she was ready.
The boss was still in a pretty bad shape, but it didn't matter anymore, not for long anyway ; she took them by surprise, no one even recognized her, and she took her creator with her.
A few months later Tony Stark made his come back for the Stark Expo, his clear blue eyes daring the world to ask questions, no one did, they applauded, without thinking. Of course he was accompanied by a young woman with red hair that he called "his daughter", and the family resemblance was obvious, mostly the eyes.
Vision smiled at her, the avengers ignored her, oblivious.
She wasn't afraid anymore.