Maria Hill, who is second in command to Nick Furry, the founder of Avengers and the director of the famous SHIELD, who always considered Maria hill as his second hand. He always sent forward Maria to lead whatever fight it was. She was given this position when the SHIELD was on the verge of destruction and end.
When Nick couldn’t trust anyone, he knew Maria would be there. She is very capable of everything; Nick feels that. She is his assistant, and a friend as well who she knows will manage things well if Nick fails to.
She was very strong and intelligent because of which she was able to manage things well. She was one of the highest-ranking agents of this SHIELD Project; she also took care of the research team, making sure no wrong research spoils anything.
She had a very powerful way of speaking and manipulating people; she knew a lot of facts but never shared. Whenever she needed to talk to someone for work for their benefit, she had some natural superpowers.
Every task Nick had planned, it was done with Maria Hill. He did not trust any other agent with the secretive facts and knowledge. She eased his work by also helping the other SHIELD Agents, and she was their guide and used to direct them.
Even those these agents she directed were invoked in recruiting the avengers, but she never went forward and played from the back, as she knew taking a step towards the avengers can cause more harm to the team than it will serve any good ever. This shows she was very practical with decisions and consistent in her mind. Now, we know why it was Maria hill who did everything with Nick furry.