Cherik

Cherik is the slash ship between Charles Xavier and Erik Lehnsherr from the Marvel fandom.

Canon
X-Men: First Class

Charles accompanied Moira MacTaggert and a US Coast Guard assault team to arrest Sebastian Shaw on his yacht. While the arrest was unsuccessful, Charles met Erik, who was trying to kill Shaw on his own. Charles prevented him from doing so and brought him the CIA's Division X facility.

Charles and Erik grew close as they began to recruit mutants to defeat Shaw. After their facility at the CIA was attacked, they relocated the team to train at Charles' mansion. There, Charles used his telepathy to help Erik unlock his potential for his powers, assuring Erik that there was good inside him. The two often played chess together as they debated how best to deal with Shaw; Charles wanted a peaceful resolution, while Erik wanted to kill him in revenge for the suffering he'd inflicted upon Erik while experimenting on him as a child.

The team was eventually deployed to help stop the Cuban Missile Crisis, which had been engineered by Shaw. After killing Shaw and donning his telepathy-blocking helmet, Erik tried to convince the others to see his side. As he spoke, Americans and Soviets ships fired on the beach they were standing on. Erik stopped the missiles in midair and turned them back on the ships. Charles tried to talk him down, but Erik was unrelenting. Unable to use his telepathy on him, Charles resorted to physically attacking Erik. The attack briefly broke Erik's concentration, but he was quickly able to regain control of the missiles. Out of options, Moira fired her gun at him to try to stop him. Erik easily deflected the bullets, but accidentally sent one flying into Charles' spine, paralyzing him from the waist down.

Charles fell to the ground in agony. Erik, completely forgetting about the missiles, let them fall safely into the water and rushed to Charles to cradle him. In a rage, he used his powers to choke Moira with her own dog tags. Charles managed to dissuade him from killing her. They parted ways, their friendship irrevocably damaged.

X-Men: Days of Future Past

Charles, who had become jaded and bitter from the loss of many of his students during the Vietnam War, turned to a serum that allowed him the use of his legs, but prevented him from using his telepathy. When Logan Howlett traveled back to the 1970s to prevent a dystopian future in which mutants were being exterminated by robots called Sentinels, Charles was reluctant to help him, but eventually relented. With the help of Peter Maximoff, they broke Erik out of his prison beneath the Pentagon, where he'd been imprisoned for his involvement in the assassination of John F. Kennedy. Upon seeing him the first time in years, Charles punched Erik in the jaw.

On their flight to Paris, they talked with each other, first arguing and then eventually playing chess as a form of truce. Though they succeeded in preventing Raven Darkhölme from killing Bolivar Trask, which had been the event that sparked the dystopian future, they were unable to capture her. She escaped, but not before Erik shot her in the ankle. Erik left by himself to kill Raven, as he was under the belief that killing her was the only way to stop the future genocide.

At the unveiling of the first Sentinels, Raven tried once again to kill Trask, though Charles was able to mentally stop her. Erik then intervened, using his powers to take control of the Sentinels and drop a stadium around them so there would be no outside interference. Charles managed to convince Raven not to kill Trask. After she left, Charles took control of Erik's mind to remove the debris that he had been pinned under. After a brief conversation, the two parted ways once again.

X-Men: Apocalypse

Charles, using Cerebro to try to locate Erik, discovered that he had been recruited by Apocalypse to be one of his four horsemen. Apocalypse noticed their telepathic conversation, and took used his powers to take control of soldiers via Charles' telepathy and force them to launch their nuclear missiles into orbit. He later teleported to the X-Mansion and captured Charles, with the intent of transferring his consciousness into Charles and using him as his next body.

During the ensuing battle with the X-Men, a conversation with Peter Maximoff and Raven convinced Erik to leave Apocalypse's side and help defeat him. After the battle, back at the X-Mansion, Charles tried to convince Erik to stay. Though he was unsuccessful, they parted on amicable terms.

Fanon
Shipping between the two was rare in the comics and during the animated series. There was more shipping during the first three films, but didn't become more common until after First Class, and became even more so after Days of Future Past.

Canon based fics will often have the two get together during various points in the films. After First Class many wrote that point being on their, mutant rectuitment mission, or when they return to Charles' childhood home to train said mutants. Days of Future Past made that point be during the plane ride to London.

On AO3 it is the most written ship for both characters. It is the most written ship in the X-Men - all media types tag, X-Men (Movieverse) tag, X-Men (Alternate Timeline) tag, and the X-Men: The Animated Series tag.

Fandom
AO3

Fanlore

Trivia

 * Charles is portrayed by Patrick Stewart and James McAvoy, while Erik is portrayed by Ian McKellen and Micheal Fassbender
 * Both pairs of actors are best friends in real life