The ♥ of the Team
Although Tony Stark is known for being a heartless industrialist, that couldn’t be farther from the truth. The fact of the matter is that Tony Start has a heart, at least, that’s what Pepper Potts seems to think.
During one of the end scenes in Iron Man, Pepper gives him a tiny replica of the Arc Reactor with the etching “Proof Tony Stark has a heart.” After that, Tony does his best to show that he does have a bit of humanity in him, which ultimately culminates when he gives his life up to save the world in Endgame. Even the Avengers acknowledge this by recreating the gift with their fists in a circle.