Tony Stark:
Clint Barton. The same story as Natasha. You still owe him though.
Steve Rogers:
Natasha Romanoff. She's always been there for you and supported you through everything and vice versa.
Bruce Banner:
Tony Stark. Though you're like his assistant, he always treated as an equal. He saw you as family and so do you.
Thor Odinson:
Wanda Maximoff. You and Wanda immediately clicked when you first met. You've been best friends ever since.
Loki Laufeyson:
Thor Odinson. You and Thor have always been close. He's really nice to you and is super sweet.
Peter Parker:
MJ. Though MJ doesn't really get along with people, she somehow got along with you.
Bucky Barnes:
Sam Wilson and Steve Rogers. You just can't pick one, they're both your best friends.