It can sometimes be very difficult to tell if two stars are really friends. Sure, they're forced to spend time together on set and on press tours. And even if they look like they're having a good time, they are actors, after all.

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That being said, Chris Evans and Sebastian Stan truly seem to enjoy each other's company. They've done tons of events, press, and movies together. But they've also shown up to support each other when they didn't have to and have nothing but nice things to say about each other. That's friendship.

10 July 2013: Evans Introduces Stan To San Diego Comic-Con

San Diego Comic-Con is the king of all comic book conventions. Every summer, stars gather to announce new projects, castings, and details about the biggest films in the industry. In 2013, Captain America: The Winter Soldier was the hot news of the con.

It wasn't Evans' first SDCC. That came in 2010 as part of Avengers press. But it was Stan's first time among the thousands of fans at the con. They spent a lot of time together that weekend during signings and panels, but given this photo, it doesn't look like it was a hardship.

9 March 13, 2014: Looked Dapper At The Winter Soldier LA After-Party

This particularly good photo heralds from the after party of The Winter Soldier premiere in Los Angeles. Evans and Stan are often in suits together since they have so many opportunities to be on the red carpet.

In this instance, Stan has gone with his classic black-on-black, while Evans has chosen a blue which brings out his eyes, according to many fans. While they may have been cajoled into posing together, they don't seem to mind the companionship.

8 March 31, 2014: Shared A Whisper At The Winter Soldier Premiere NYC

Not even a month later, the two were brought together again for the New York City premiere of the same movie. The paparazzi captured this genuine moment between Evans and Stan.

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Given that the bare minimum would be to simply stand next to each other, this seems a lot more like friendship. They're probably just saying hello, but there could be an inside joke thrown in there too. We'll never know (and that's okay).

7 June 2014: In The Spotlight At Wizard World Philadelphia

Still riding high off the success of The Winter Soldier, the pair came together again at the Wizard World comic con in Philadelphia. The appearance is, of course, part of their job. Nevertheless, the two appeared friendly at the convention.

The two don't attend too many conventions other than San Diego, but this is one of many to come. While Captain America: The First Avenger was technically their first step on the way to stardom, The Winter Soldier catapulted the pair's friendship into the spotlight.

6 March 2016: They Survived A Buzzfeed Tumblr Q&A Together

The test of a true friendship is a Buzzfeed Tumblr Q&A. Tumblr can be a dangerous place for stars. It's full of genuine adoration, sure, but there are other corners full of a more...intense kind of adoration. Nevertheless, Evans and Stan went through an Answer Time together- and survived.

Buzzfeed picked easy questions like, "how will Bucky celebrate his 99th birthday?" and "sum up Civil War in three words." Short, sweet, and to the point. Evans and Stan handled the attention like champs.

5 April 2016: Chubby Dumpling

In a spectacularly delightful interview from the Captain America: Civil War press tour in China, Evans discovered some of Stan's Chinese nicknames and the two prove their genuine rapport. "You have some nicknames in China," the interviewer begins. Stan nods, "384. Chubby Dumpling." The interviewer continues but Evans interrupts with glee, "Wait a minute! Wait a minute!"

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Stan explains the meaning behind 384, but Chubby Dumpling "is just natural". The interviewer asks which one he prefers. Stan answers 384 but Evans declares that he prefers Chubby Dumpling. The interview continues but Evans just can't move on. "Chubby Dumpling," he whispers to himself not ten seconds later, laughing again. "It's the best," he comments to no one.

4 June 2016: "Seb, Back Me Up!"

At Wizard World Philadelphia, Evans, Stan, and friend and co-star Anthony Mackie gathered to discuss their experiences on set. The three reminisced about their time filming Civil War. In it, Evans drives the other two in a tiny car.

Mackie accused Evans of being a terrible driver. "That's outrageous! I drove that car phenomenally!" Evans shot back. "Seb, back me up!" He answered. "You did, you did," Stan assured him, coming to the rescue. That's true friendship.

3 2014-2016: The Compliments

Even when the other isn't around, Evans and Stan have nothing but kind words for each other. "I wish you guys could know Sebastian," Evans said during press for The Winter Soldier, "he's the sweetest human being on the planet. He's such a good guy and he's so positive."

Stan returned the flattery years later while filming Civil War. "I love Chris," Stan commented while still in costume, "He's awesome. He's an incredibly generous actor." Stan went on to compliment Evans on his openness as an actor and his ability to be a team player.

2 January 2018: Catered To Fans At Ace Comic-Con

Evans and Stan are convention professionals by this point. They're used to taking directions from fans who put them in many, often intimate or ridiculous poses. This photo may be one of those fan-directed poses, but their smiles look pretty genuine.

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There are few things better in this world than intimate male friendships. Ian McKellan and Patrick Stewart are a great example. Normalize soft male friendships!

1 March 2018: Stan Supports The 'Stache At Lobby Hero

Though Evans and Stan have had fewer scenes together in Avengers and thus, fewer press responsibilities. That hasn't kept them apart, however. Evans had his Broadway debut in 2018 in the play Lobby Hero. Evans' haircut and mustache, seen above, were for his character.

Stan attended the play's opening night to show support for his friend. The two posed for photos at the after-party. This is one circumstance that wasn't part of any contract. If the other facts weren't compelling, this show of support will convince you that these two stars are truly friends.

NEXT: Marvel: 5 Of The Most Heroic Things Bucky Barnes Has Ever Done (& The 5 Worst)