Anthony Stark came from a dysfunctional and discordant family life. He had a broken childhood which he spent trying to earn his father's affection and time. The hurt that he carries as a result and how it manifests is what we see in his careless playboy attitude and demeanour. We see that he doesn't let people in, except for a close few like Obadiah, Pepper and Rhodey. Unfortunately Obadiah ends up betraying him for the prospect of money and fame, destroying the respect, trust and bond that Tony had formed with him. But, we see him gradually open up, start behaving more like he wants to and showing his care to the people he trusts and loves, those including the Avengers team after the events of the first Avengers movie. His character development is very strong and very heart capturing from his origin movie itself. When in Avengers: Endgame they show that he'd managed to build a happy family life for himself with Pepper as his wife, and a 5 year old daughter, Morgan, it is a truly inspiring and emotional storyline. We see him be absolutely wonderful with Morgan, and this life and his daughter are the reasons he turns down the rest of team when they come asking for him to help them find a way to stop Thanos from wiping out half the population. But, he ends up spending time and figuring out the solution on how to time travel because, one, he has a bleeding heart and cares about the lives that were lost, and two, because Peter Parker was one of those people who got dusted. His mentor-mentee bond with Peter was not that simple, and not so professional. He had a true sense of responsibility towards him because he saw him as something more.