Robert Downey Jr. has responded to Chris Evans' Captain America thank you letter, in which the latter reflected on wrapping Avengers 4. The two actors are currently in Atlanta, where reshoots for the upcoming Marvel film are taking place. Besides Downey and Evans, other actors - including Jeremy Renner, Chris Hemsworth and Tessa Thompson, Paul Rudd and Scarlett Johansson, and Elizabeth Olsen and Pom Klementieff - have all been spotted on set. Reshoots began in September. According to Mark Ruffalo, these reshoots will "finish the movie," rather than just fixing scenes or adding additional lines.

These last days on set are sure to be an emotional period for the cast. Many of them have been playing these characters since MCU Phase 1, and have worked together onscreen almost as long. The original Avengers are so close they even got matching tattoos. Saying goodbye at the end of filming is sure to be bittersweet, as for some, it'll be for the last time. Evans posted a tweet commemorating his wrap on Avengers 4, and saying what an honor playing Steven Rogers had been. Of course, this caused the MCU fandom to break down as well, believing that this seals Cap's Avengers 4 fate. Regardless of if the character lives or dies, the film will most likely be the end of the line for Evans, whose contract is up.

Related: Everything We Know About Avengers 4's Reshoots

Robert Downey Jr. subsequently responded to Evans' emotional tweet with one of his own. He posted: "We all know who the real sheriff in town is", with an image of Woody and Buzz from Toy Story. Buzz is dressed in Iron Man armor, while Woody is decked out in red, white, and blue Captain America regalia. The poster reads, "To Infinity War and Beyond" a cute nod to both the Avengers: Infinity War title and the saying from the animated Pixar film. Check out the tweet and image below.

Update: Chris Evans has since responded to RDJ's response. Check it out below.

Iron Man and Captain America have been mainstays of the MCU since 2008 and 2011, respectively. The actors have become as iconic as the characters they play, and oftentimes it's hard to draw a line between the two. It's almost impossible to imagine the movies without either of these characters, but it's a reality Marvel fans are slowly realizing they're going to have to face very soon.

Avengers 4 will mark both a beginning and an end of sorts. While it's likely time to say goodbye to actors like Evans and Downey Jr., the next round of MCU movies will also usher in a new era of characters. Heroes like Captain Marvel, Shuri, Black Panther, and Valkyrie will step up to take the place of the fallen or retired. The future of Marvel Studios is in good hands.

More: Mark Ruffalo Fake Spoils Avengers 4 Title; Directors Fake Fire Him

Source: Robert Downey Jr.