I keep thinking about that one story, 'Unbreakable Ties,' on AO3. It's a modern AU where Mark never gets powers, and William is basically his human anchor through all the regular, messy stuff of growing up—college stress, family drama, the works. The fic spends ages on William's quiet struggle with self-worth, feeling like he's always in the shadow of his superpowered best friend. Watching him find his own voice and confront his dad about his legacy was way more satisfying than any superhero fight scene.
The writer uses these small, domestic moments, like William fixing Mark's laptop or them just arguing over takeout, to build this incredible emotional foundation. You really feel the shift from him being the 'sidekick' to an equal partner, and it makes the eventual confession of feelings feel earned, not just tacked on. Honestly, I sometimes skip to the chapters focused on William's POV on a re-read; that's where the real heart of the story is for me.