Well, one possibility could be Deadpool driving the Avengers crazy with his non - stop chatter and crazy antics. He might constantly break the fourth wall in the middle of a mission, making the Avengers wonder what on earth he's talking about. For example, he could start making jokes about how Captain America's suit is so old - fashioned compared to his own while they're in the middle of a fight against a powerful villain.
There is a fanfiction titled 'Deadpool Saves the Avengers (Sort of)'. The plot is that Deadpool accidentally stumbles upon a situation where the Avengers are in trouble and his unorthodox methods end up helping them, although not in the way they expected. It's full of hilarious moments and unexpected twists that are typical of Deadpool stories.
Iron Man would be a likely candidate. Tony Stark is known for his sense of humor and ability to tolerate eccentric personalities. He might see Deadpool's skills and be interested in using him for certain missions, while also enjoying the banter.