WARNING: MILD SPOILERS AHEAD FOR AVENGERS: ENDGAME
If you walked out of Avengers: Endgame asking "Who's that random kid?", you weren't alone.
As much as audiences were revelling in the movie that marked the culmination of 11 years and 22 films — and over 45 hours of screen time — the fleeting appearance of a strange character in a pivotal scene threw everyone for a loop.
Who the hell was that gawky, silent teenage kid standing with, but slightly apart from, all our heroes and their loved ones at the end of the film?
That character is Harley Keener, and he's played by 17-year-old actor Ty Simpkins.
If the character's name is familiar, it's because we've met him before — but he looked a lot different then.
Harley is the young boy who helped Tony Stark in Iron Man 3. Back then, he was a wee tyke, barely into the double digits.
He met Tony when Stark was raiding his family's garage in rural Tennessee after getting himself stuck when his latest prototype armour failed and stranded him.
Harley is a mechanically-inclined inventor himself and ultimately helped Tony to rebuild his suit, while also helping him to snap out of his funk. He's also pretty handy with a flash grenade.
After Tony exposed the Mandarin as a fake and saved the president from an assassination plot, he didn't forget his little assistant.
Last we saw Harley, the kid had discovered a treasure trove of computer and robotics equipment, a gift from Tony.
It could be the now-grown-up Harley's presence in the closing minutes of Endgame is merely because of his bond with Stark, who once told him they were "connected".
More likely, it has a deeper significance.
Marvel never does anything as a throwaway, there's always something in the works and Harley's blink-and-you'll-miss-it presence signals the studio has something much bigger planned for him.
Could he follow in the footsteps of his one-time mentor?
Avengers: Endgame is in cinemas now