Throughout the MCU’s 23-part “Infinity Saga,” Tony Stark and Steve Rogers easily had the most important relationship in the Avengers. Steve was the leader of the team and Tony didn’t play well with others, so they were antagonistic towards each other from jump. They grew into unlikely friends based on mutual respect before being torn apart as that friendship was tested, and they eventually let go of their resentment towards each other and made amends as they joined forces to save the world, once and for all. Here are 5 Times Tony Stark And Steve Rogers Were Best Friends (And 5 Times They Were Each Other's Worst Enemy).

RELATED: MCU: 5 Reasons Iron Man Is The Star Of The Infinity Saga (And 5 Why It's Captain America)

Best friends: “I lost the kid.” “Tony, we lost.” (Avengers: Endgame)

When we catch up with Tony Stark in Avengers: Endgame, having been stranded on Titan with Nebula following the Snap at the end of Infinity War, he’s looking emaciated and defeated. The Benatar has run out of fuel and food rations, so Tony records a message that he believes will be his heartfelt farewell to Pepper. He drifts off to sleep, fully expecting to die in the night. When Carol Danvers shows up to save him, she gives him a second chance at life. Pepper survived the Snap, so Tony didn’t lose everything. But he almost did. He gravely tells Steve, “I lost the kid,” and Steve corrects him: “Tony, we lost.”

Worst enemies: Tony taking Steve’s shield from him (Captain America: Civil War)

Tony takes Steve's shield in Captain America: Civil War

At the end of Captain America: Civil War, Tony Stark is heartbroken to discover that Bucky Barnes killed his parents while operating as the Winter Soldier, and worse yet, Steve Rogers knew about it. This leads to a brutal fight between the three that ends with Tony lying in the dirt, feeling beaten and betrayed, as Steve leaves with Bucky.

RELATED: 10 Best Steve & Tony Moments in the MCU

Tony demands that Steve leave his shield behind, because his father made it for him and he doesn’t deserve it. Steve simply drops the shield to the floor, relinquishing it to Tony without an argument, and walks off with his friend.

Best friends: Tony giving Steve’s shield back (Avengers: Endgame)

Avengers: Endgame Tony Steve shield

In Avengers: Endgame, after a five-year time jump, Scott Lang emerges from the Quantum Realm with a plan to travel through time, collect the Infinity Stones, and save everybody who died in the Snap. He takes this idea to Steve Rogers, who takes it to Tony Stark. Although he’s initially reluctant, Tony accepts the challenge and tells Steve that he wants to let go of the resentment he feels towards him because it’s not healthy. So, Tony returns to the Avengers’ compound and gives Steve’s shield back to its rightful owner. Then, Tony jokes, “Will you keep that a little quiet? Didn’t bring one for the whole team.”

Worst enemies: Arguing on the Helicarrier (The Avengers)

Chris Evans and Robert Downey Jr. as Steve Rogers/Captain America and Tony Stark/Iron Man looking sideways in The Avengers

When Tony Stark and Steve Rogers first meet in The Avengers, they don’t get along. Essentially, Tony and Steve are two completely different people. One is a patriotic soldier, the other privatized world peace. One is a man out of his time, the other is a futurist. Joss Whedon did a phenomenal job of showing their ideologies clash, including two brilliant lines that would be paid off beautifully seven years later (11 in story years) in Avengers: Endgame. Steve told Tony, “You’re not the guy to make the sacrifice play.” Tony would make the sacrifice play to save the universe from Thanos in the end. Tony told Steve, “You’re a lab rat, Rogers. Everything special about you came out of a bottle.” Steve would prove this to be untrue when he was worthy of lifting Mjolnir.

Best friends: Chopping wood together (Avengers: Age of Ultron)

Not all Marvel fans were taken with the detour to Hawkeye’s farm in Avengers: Age of Ultron, with some feeling that it slowed down the plot and placed the focus on the least interesting character. However, it provides an important emotional juncture for Steve Rogers and Tony Stark. Steve gets a glimpse of the family life he fears he’ll never have, while Tony discusses his worst nightmare with an incognito Nick Fury. The pair also bond as they chop wood together. Tony tells Steve not to take wood from his pile, despite the fact that Steve’s pile is much bigger than Tony’s.

Worst enemies: “S**t!” “Language...” (Avengers: Age of Ultron)

In the opening scene of Avengers: Age of Ultron, as Earth’s mightiest heroes storm the Hydra compound of Baron von Strucker in Sokovia, Tony is hit with the compound’s deflective shields and cries out, “S**t!” Then, a motorcycle-straddling Steve sternly tells him, “Language...” For the rest of the movie, Tony and the other Avengers won’t let Steve live that one down. It was a funny moment, but also represents the key differences between the characters. The central dynamic is that Steve is old-fashioned and Tony is a futurist. Steve is all about censoring bad language, but Tony has no such qualms.

Best friends: Steve sending Tony a cell phone (Captain America: Civil War)

Iron Man Tony Stark Captain America Civil War Injuries

Tony and Steve’s relationship was torn apart in Captain America: Civil War, and surprisingly, it wasn’t mended again by the end of the movie. But Steve did offer Tony an olive branch, sending him a care package via FedEx with a note attached to it telling Tony that if he ever needs him to join him in a fight, he’ll be there.

RELATED: Captain America: Civil War: 5 Characters Who Picked The Right Side (& 5 Who Should've Been On The Other Side)

As he sifted through the FedEx package to see what Steve had sent him, Tony received a call from General Ross, telling him there’d been a breach at the Raft. Knowing that this breach was Steve Rogers breaking his friends out of the seafaring prison, Tony put the General on hold.

Worst enemies: Tony blaming Steve for the Snap (Avengers: Endgame)

Tony yells at Steve in Avengers Endgame

When he returned from space after the Snap and reunited with Steve Rogers, having been personally defeated by Thanos, Tony Stark blamed him. The way he saw it, Earth could’ve been protected from Thanos if he’d been allowed to create a planet-wide security system like he proposed in Avengers: Age of Ultron. Tony told Steve, “What we needed was a suit of armor around the world! Remember that? Whether it impacted our precious freedoms or not, that’s what we needed! ... I said we’d lose. You said, ‘We’ll do that together, too.’ Guess what, Cap, we lost. And you weren’t there.”

Best friends: “Do you trust me?” “I do.” (Avengers: Endgame)

Tony talks to Steve in Avengers Endgame

The most important part of the “Time Heist” in Avengers: Endgame was traveling back to New York in 2012, because three Infinity Stones were there at that time: the Mind Stone, the Space Stone, and the Time Stone. Iron Man, Captain America, Ant-Man, and the Hulk were on this extraction team. The Hulk got the Time Stone and Cap got the Mind Stone, but Iron Man and Ant-Man dropped the ball on the Space Stone, accidentally allowing Loki to disappear with it. Tony concocted a plan to travel to a military base in 1970, where S.H.I.E.L.D. kept the Space Stone and Hank Pym had some Pym Particles that would allow them to get back to the present. Tony asked Steve, “Do you trust me?” and Steve said, “I do.”

Worst enemies: “He’s my friend.” “So was I.” (Captain America: Civil War)

Sad Tony Stark in Civil War

When Tony Stark found out Bucky Barnes assassinated his parents when he was brainwashed by Hydra, all Tony wanted to do is kill Bucky. The truce the characters just made was immediately thrown out the window as a brutal fight erupted between Tony and Bucky. Steve Rogers had a choice to make. Tony is his new friend and comrade, but Bucky is his childhood best friend. Steve could either let Tony kill Bucky or fight Tony to save Bucky. He went with the latter option, because Bucky has been there for Steve since he was a kid. As he began fighting Tony, Steve said, “I’m sorry, Tony. You know I wouldn’t do this if I had any other choice, but he’s my friend.” Tony bluntly said, “So was I.”

NEXT: Avengers: Endgame: 5 Reasons Iron Man Got The Best Ending (& 5 Why Cap Did)