Doctor Strange's "grand calculus" line in Spider-Man: No Way Home being a lot darker than audiences may realize. The former Sorcerer Supreme's character arc in the MCU has changed dramatically over the years. With him more involved than ever in the Mystic Arts during Phase 4, Stephen Strange has been going down a darker path as he dabbles with dark magic and continues to be reckless. The first signs of this began when he helped Peter Parker after his identity is revealed to the world.
It is explained throughout No Way Home and Doctor Strange 2 that there is "frighteningly little" known about the Multiverse, and MCU's Earth-616 Doctor Strange is still willing to take a huge risk by messing with the fabric of time by erasing memories - despite being the same version of Strange that was fine with letting people die in order to protect the Time Stone in Avengers: Infinity War.
How Doctor Strange's Characterization Is Different In No Way Home
When the first trailer for Spider-Man: No Way Home released, it was clear to many viewers that Stephen Strange was acting very differently. In the film, he agreed to help Peter Parker out and break the rules of magic, looking past the consequences. It didn't appear that this Strange was the same one last seen in Avengers: Endgame. No Way Home proved Doctor Strange was right to not want to use the spells initially, but he was easily convinced that he should take the risk. It's naturally confusing that this is the same Strange that was insistent on looking through over 14 million futures and focusing on one in order to make sure the Avengers defeated Thanos, as that version of Strange was characterized as being willing to make sacrifices in order to ensure the safety of the timeline - something No Way Home Strange doesn't seem to be as invested in.
Strange's "Grand Calculus" Line Proves All Strange Variants Are Trouble
Defender Strange uttering the "grand calculus" line confirmed similarities between his variants, just like how every Peter Parker shared similar traits. This particular version of Doctor Strange proves all of his variants are dangerous because of what they are willing to sacrifice. Earth-616, Earth-838 and Defender Strange all allowed themselves to let people perish in order to accomplish their missions, while others like Sinister Strange and Strange Supreme from What If...? manage to destroy universes to appease their own desires.
Many versions of Doctor Strange become evil because of their inability to let go of things and their own narcissistic tendencies. While Strange tries to do whatever he can to protect reality, he and his other variants often act too impulsively to meet their goals, as seen in Doctor Strange in the Multiverse of Madness. Earth-616 Strange didn't seem to even consider hearing Peter Parker out once he figured out a way to save the Multiversal villains in Spider-Man: No Way Home, suggesting Doctor Strange first became a darker character in the latter film and is continuing to go down a darker path.
