Tony:
Fe man. It means Iron man and you refuse to actually call him iron man so you use other words.
Steve:
My man <3 . You used to have him as Capsicle until he saw it and threw a 5 year old fit.
Clint:
Honey boo boo. He sometime acts like her.
Thor:
Mew Mew. You can't pronounce his hammer's name.
Loki:
Honey Badger. He looks nice but has a dark side.
Bruce:
Big green rage monster. Tony put it in there.
Bucky:
Metal arm. He doesn't know it's this and you won't let him.
Wanda:
Wicked witch of the west. Well her name is scarlet witch and she loves the play wicked.
Natasha:
Spiderman. She hates this name.
Pietro:
Cupcake. He is sweet like one.