Here's why Doctor Strange's work with the Avengers is likely to make his former fellow Sorcerer Karl Mordo hate him even more. While Chiwetel Ejiofor's character disapproved of Doctor Strange’s (Benedict Cumberbatch) lack of respect for natural law at the end of Doctor Strange, it’s likely that Mordo feelings will intensify now that he’s joined the ranks of Earth's Mightiest Defenders. From using the Time Stone to explore possible futures to handing over the Time Stone to Thanos (Josh Brolin) to save Iron Man (Robert Downey Jr.) in Avengers: Infinity War, Strange has done plenty of things since he and Mordo parted ways that Mordo would disapprove of, including the fact that Strange helped the Avengers defend Earth from Thanos in both Infinity War and Avengers: Endgame.

As established in Doctor Strange, Mordo believes that natural law shouldn’t be tampered with, but rather defended. Mordo began to question the honor of the Masters of the Mystic Arts after learning that the Ancient One (Tilda Swinton) drew power from the Dark Dimension in order to extend her lifespan. After the Ancient One’s death, Strange agreed with her belief that sometimes you must break the rules in order to serve the greater good and later used that flexibility to defeat Dormammu at the end of Doctor Strange. Strange broke the natural laws of time by creating a time loop to entrap Dormammu and only granted the inter-dimensional being freedom once he agreed to leave Earth. Seeing how easily Strange bent the rules to serve his own purpose, it caused Mordo to leave the Masters of the Mystic Arts, reexamine the role of a sorcerer and began stealing the abilities of sorcerers who abuse their power. 

Related: Infinity War: How Doctor Strange Learned So Much In Just Two Years

According to Mordo's logic, assisting the Avengers lies outside of Strange’s jurisdiction as a sorcerer. In Doctor Strange, Wong (Benedict Wong) points out the distinction between the roles of a sorcerer and the Avengers in their universe. “While heroes like the Avengers protect the world from physical dangers, we sorcerers safeguard it against more mystical threats,” says Wong. After Wong explains that the first Sorcerer Supreme Agamotto built the three Sanctums to generate a protective shield around their world in order to defend against the dimensional beings that threaten their universe, Mordo states, “The Sanctums protect the world and we sorcerers protect the Sanctums.” However, after being saved from Ebony Maw (Tom Vaughan-Lawlor) by Iron Man and Spider-Man (Tom Holland) in Infinity War, Strange chose to join the Avengers in a fight against Thanos, a physical threat from their own dimension, instead of returning to Earth to guard the New York Sanctum with Wong. 

Karl Mordo at Kamar-Taj in Doctor Strange

From Mordo’s perspective, Strange should’ve returned to Earth to protect the Sanctum from any further threat Thanos’ army posed, similar to the Ancient One’s passive role during the Battle of New York from The Avengers. In Endgame, it’s revealed when Bruce Banner (in his Smart Hulk form) attempts to retrieve the Time Stone from the New York Sanctum that the Ancient One was busy guarding it instead of helping the Avengers defeat the Chitauri. Since the Ancient One defended the Sanctum and not Earth during an alien invasion, Endgame reveals the path Strange should’ve taken as a sorcerer during Infinity War's similar battle. Because Strange took on a role that falls more under the purview of the Avengers, which goes against Mordo’s view of tradition, Strange is giving the villain more of a reason to destroy him in the future, specifically for betraying what a sorcerer’s role is supposed to be. 

Not only does Strange change a sorcerer’s role for himself, but for the other Masters of the Mystic Arts. While Strange hasn’t yet earned the title of Sorcerer Supreme, Strange appears to have some influence amongst the other sorcerers since Strange recruits them offscreen to fight during the Battle of Earth in Endgame. Since everyone in the universe was affected by Thanos’ snap, the Battle of Earth may have been a special case, but it appears that the Sanctums were unguarded while the sorcerers assisted in the final battle against Thanos. Now that Strange has changed the definition of a sorcerer’s role to include defending against physical threats and corrupted the other sorcerers, Mordo will most likely have more vengeance to enact against Strange in the sequel, Doctor Strange in the Multiverse of Madness

More: How Many Duplicates Did Doctor Strange Make Fighting Thanos In Infinity War

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