The relationship between Clint Barton and Natasha Romonov was what one would call a work partner one, maybe even a romantic one but alas no one would ever have guessed what they really were...

Siblings. They were Siblings, of course only Nick Fury and they themselves knew that but it still was... Weird to find out that people thought they were dating, and maybe even, god forbid, married! Well to say they were unpleased when they heard that was of very, very large understatement, they were pissed, to the max I mean the others didn't know they were related, much less very closely, but it still unnerved them. So when Tony Stark came up to them and started asking a lot of questions that see,Ed like he knew that they were related they were quite surprised and in return asked him questions, after answering his of course and their last and final question was 'Why did you ask us these questions and what did you figure out from them'. They were not very surprised that his answer to the first part off their question was 'for Reaserch' but for the last part he bolted off to his lab leaving them both surprised and in his dust.