10 MCU Movie Teases That Went Absolutely Nowhere

5. The "Exceptional Gene"

What Happened

As revealed at the end of Captain America: The Winter Soldier, HYDRA had procured Loki's sceptre (somehow) and were using it to experiment on "volunteer" subjects to empower them. Though lots of subjects had been killed by the process, Scarlet Witch and Quicksilver survived, each with different power sets.

What it Teased

The presence of exceptional individuals with latent powers that could be encouraged to come out with some assistance - in this case an Infinity Stone. The fact that the twins had DIFFERENT powers suggested that the sceptre merely awakened something in then, rather than them gaining something entirely new from the Stone.

So, that would suggest that there could be others who could potentially be empowered in the future of the MCU, given the right circumstances.

But Then...

The tease was essentially Marvel's way of dealing with not having access to mutants, but the exceptional gene began and ended with the twins in the MCU. It's literally never been explored again. Perhaps Kevin Feige knew he was going to get his hands on Fox's mutants eventually and just abandoned the whole genetic question?