Often, they're portrayed as very close friends with a deep understanding of each other. They trust one another completely and are always there to have each other's backs in dangerous situations.
In many fanfictions, their relationship is depicted as a partnership that goes beyond just being Avengers. They share a bond that was formed through years of fighting side by side. They can communicate without words, and their relationship is a source of strength for both of them. Some fanfictions might even explore a romantic relationship that blossoms during the high - stakes events of Infinity War, with stolen glances and small gestures of affection in the middle of all the chaos.