MCU: The Worst Thing EVERY Avenger Has Done

Quicksilver showed himself to be a true hero when he sacrificed himself for the greater good while his sister Scarlet Witch quickly became one of the Avengers' most powerful warriors. However, it wasn't always heroics for the Maximoff siblings as the pair had something of a checkered beginning in the MCU.

Still vengeful over the death of their parents, the pair held Tony Stark personally responsible for the tragedy they suffered and, as a result, they willingly aligned themselves with villainous A.I. Ultron in a rash decision that seemed like the right thing to do at the time.

To their credit, they soon realised the dangers that awaited mankind under Ultron's grip and turned against him, assisting the Avengers in their battle and ultimately helping to defeat him once and for all.