When Miranda Cobb tries to stop her car accident with her boyfriend it causes more damage than harm. Her parents make the decision that it's time for their daughter to go with the Avengers.
When you join the avengers things start to go south tony and Steve are arguing and you are scared because you have trauma from when you where a kid with your parents hitting you or just arguing and when Natasha sees you like this all scared she can always comfort you when this thing happens and slowly that how the love story began.