The dynamic between Charles Xavier/Professor X and Erik Lehnsherr/Magneto has always been an integral part of the X-Men films and comic books. Even when not in the shoes of dual protagonists, the two Marvel mutants have driven the plot forward with their tense relationship and their opposing points of views. What’s helped even more in this matter, at least in the movies, is the chemistry between the actors who have portrayed these characters over the years.

RELATED: Fox's X-Men: 5 Times Professor X And Magneto Were On Different Sides (And 5 Times They Saw Eye To Eye)

Yet, because of a variety of reasons—one of them being the paucity of time—a lot of stuff has been left unsaid between the two in their movie portrayals. We haven’t seen, for instance, how much they have both relied on each other despite their differences—with Professor X entrusting X-Men’s reigns to Magneto quite a few times, and the latter only trusting the former when a child of his is in peril. One by one, these incidents have added layers to what is probably the most complicated friendship in fiction.

10 Their First Meeting Was Quite Subdued

Professor And X Magneto Meet For The First Time

On screen, specifically in the film X-Men: First Class, Charles and Erik meet each other for the first time when Erik is trying to manipulate Sebastian Shaw's submarine while being underwater himself. Xavier is the one to telepathically convince him to let go otherwise he'd drown.

In the comics, the two meet at a hospital in Israel, though, through their conversations, Charles is quick to notice Magnus' (the name Erik goes by) mental strength as a mutant, he doesn't outright call him out on it. Their first meeting is a lot more subdued, brimming with unsaid thoughts, than the one in X-Men: First Class.

9 Charles Helps Magneto Change Into A Better Mutant

 Magneto Atones For His Sins

Following the events of Secret Wars, written by Jim Shooter with art by Mike Zeck and Bob Layton, Magneto finds himself to be in a different state of mind. There are two aspects to this: firstly, during his time on the planet Battleworld he was placed on the side of the heroes by the evil mastermind Beyonder and had to fight the villains of the Marvel world. Later, when the X-Men request his help to fight a resurgent Beyonder, he joins them in the effort and stays on with them for a while having defeated the super-villain. In Charles and the others' company, he begins to question his past actions.

His reformation doesn’t stop there; he now wishes to atone for his sins. In an effort to do so, he willingly stands before a court to receive punishment for all that he has done wrong in the past. He hasn't had a moment such as this in any of the films, yet.

8 Professor X Asks Magneto To Take Over X-Men For A While

Professor And X Tells Magneto His Dying Wish

Xavier is there, in the courtroom where Magneto is standing trial for his horrific past, when Baron von Strucker’s children storm into the room and attack the two of them. Xavier is grievously injured but still he doesn’t forget about his X-Men. He entrusts the responsibility of his school and his team to Magneto, even though he doesn’t think himself to be worthy. But then again, there’s no one he admires more than Erik.

RELATED: Marvel: 5 Best Professor Xavier Deaths (& 5 Worst)

Afraid that the other mutants won’t accept his authority, or be antagonistic towards him, Magneto takes on the disguise of Michael Xavier, a supposed cousin of Charles, and begins to lead the X-Men.

7 The Darkness In Their Minds Creates A New Entity

Professor X As Onslaught

There have been many iconic rivalries in the history of comic books, but none of them have led to the creation of something like Onslaught. Without a doubt, that entity can be called the most unusual aspect of the relationship between Charles and Erik.

The sentient entity is borne from the darkest regions of the two mutants’ consciousness, created when Professor X finally gets fed up with Magneto’s antics—wherein he tortuously extracts the Adamantium from Wolverine’s form—and shut every mental process inside Magneto’s mind. It’s a very powerful psionic connection, which allows every piece of grief and anger within the two to latch onto each other and create the being called Onslaught—which coexisted within Professor X.

6 The Two Rebuild Their Friendship And An Island

Magneto Watches Over Genosha

Annihilation is imminent in the film X-Men: Days of Future Past, in which Sentinels are chasing mutants and killing them. So dire is their situation that even Magneto and Professor X are on the same side in a rare moment for the movies.

In the comics, though, they put aside their differences quite a few times. And one of them is when a group of Sentinels attack Magneto and the residents of Genosha, leaving widespread destruction in their wake. Millions are dead, and even Magneto is supposed to have perished. But when Charles comes to visit the island, he sees his old friend alive recovering from the attack. It is an important moment for them, more so since only a few scenes prior to it Erik had used Charles as bait in his nefarious plan.

5 Magneto Trusts Professor X With His Daughter’s Life

Professor X Helps Magneto's Daughter

A major plotline in House of M, written by Brian Michael Bendis and illustrated by Olivier Coipel, is Wanda Maximoff's unstable state during which she takes control of reality and begins to warp it. This proves highly dangerous, of course, so Doctor Strange places her in a coma to halt her actions. But Magneto, her devoted father, hears her through their connection and time-travels to the past to swoop in before Doctor Strange can immobilize her.

RELATED: MCU: 5 Times Scarlet Witch Was A Hero (& 5 Times She Became A Villain)

Even though he “saves” her from the Avengers, he is unable to treat her mind and control her increasingly unstable powers. He is vulnerable himself and in his hour of need he only allows someone he truly trusts—Professor X—to come and help him treat Wanda.

4 Magneto Regrets His Past Actions

Magneto Forgives Professor X

Despite his tendency to solve problems with violence, Magneto is not above pursuing peace especially when he is repentant. Once he realizes his mistake, he almost always makes it up to whoever it was he had wronged.

When he arrives at Utopia, in order to help Cyclops and his X-Club keep their little haven afloat, he is conscious of how he must work hard to gain the X-Men's trust. When Professor X later lashes out on instinct and attacks him, he is gracious in accepting his faults—something he never is in the films. Even more so when Charles apologizes for the undeserved attack. He is very understanding and level-headed in response.

3 The Two Build A New Mutant Nation

Marvel Comics' Professor X and Magneto walk through Krakoa.

The main bone of contention between Charles and Erik is the past, present, and future of mutants. While the professor wants to a find a peaceful way to ensure that his kind aren’t persecuted, Magneto believes that all mutants are superior to humans and they don’t really need any sort of cooperation with humans and wants to take their place in the world. Essentially, what both of them want is for mutant-kind to have a bright future; it’s just that they can’t find any common ground to work together on this.

But in House of X by writer Jonathan Hickman and artists Pepe Larraz, R.B. Silva and Marte Gracia, there is an attempt to build such a future. Charles, Moira X, and Magneto all come together to lay the foundation for a mutant-only country called Krakoa. It takes some convincing on both their sides but the two agree to join forces.

2 Magneto Establishes X-Men After Professor X’s Death

Magneto And His X-Men

David a.k.a. Legion, Charles' son with Gabrielle Haller, is immensely powerful but he is also quite unstable and, at times, out of control. That is the burden of his abilities. When he gets it in his head that he must travel back in time and kill Magneto before he causes all the anguish to his father, he ends up assassinating Charles instead.

Distraught, Magneto decides to take up his friend's dream and adopts a more peaceful outlook. Indeed, he is the one to establish X-Men in this reality. There is a film counterpart to this when, in X-Men: The Last Stand, Magneto tearfully watches on as Jean kills Charles. Unlike the comic books, though, his desire to see his plan succeed outweighs his grief over Charles.

1 Magneto Names His Son After Professor X

Magneto With His Son Charles

Having lost Charles in the most terrible way and seen his friend get accidentally killed by his own son, Magneto suffers insurmountable pain for a long time. There is a need in him to keep Charles' memory close to him, a need in him to honor the man in a manner beyond managing the X-Men.

So, after Magneto marries Rogue—his lover in the "Age of Apocalypse" story arc—and they go on to have a son, he decides to name his child after the mutant who is gone but not forgotten. The film version never does such a thing; Magneto's only confirmed child is a daughter called Nina, who is tragically killed at a young age.

NEXT: X-Men: 10 Comics That Explore Professor X & Magneto's Relationship