This is the underdog story of this list. When we met Wanda (Elizabeth Olsen) in "Age of Ultron," she was saddled with a ridiculous accent. Vision (Paul Bettany) was an obnoxious robot guy. When we checked in on them in "Civil War," they were flirty friends. In "Infinity War," their relationship was supposed to be a major plot point, but it didn't really hit because we'd barely seen them on screen.
And then "WandaVision." Wanda turns her grief at losing Vision into a creative, messy, painful force, building a whole life for them and causing incredible damage. You were invested in them. It felt like a magic trick.
The one thing that keeps them from the number one spot is Vision's bizarre absence from "Multiverse of Madness." He doesn't even get a mention. It's an odd choice when Wanda's grief is still such a big character motivation.