The MCU has been criticized for not following through with character deaths for a long time. Bluffs like Loki's multiple tricks and Avengers: Endgame that Loki, Gamora, Vision, Black Widow, and Tony Stark met their tragic and definitive end. Phase 4 will deal with the aftermath of these deaths, starting with Vision and Quicksilver. Although they seem to be returning from the dead, nothing is as simple as it seems.

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Vision's synthezoid nature makes him an easy subject to reanimate through Wanda's magic. In fact, Agents of S.H.I.E.L.D.), much less one who died several years beforehand.

As godlike as Wanda's abilities appear to be, they still follow somewhat logical rules. She possesses an ever-growing assortment of magical abilities such as telekinesis, telepathy, mind control, and matter manipulation, but none of them are connected to the soul, anima, or essence of living beings. Sure, at this rate Wanda may become so powerful that she'll eventually be able to break all logic in the multiverse, but she clearly wasn't able to toy with non-synthezoid deaths when Westview was created. That's why she can't revive Sparky or Pietro.

Death is such a serious matter in the MCU that it's tied to the Soul Stone. This Infinity Stone, in itself a universal relic, requires the death of a loved one to be claimed and connects the wielder with the Soul World. Even then, a fully-stocked Infinity Gauntlet wasn't powerful enough to bring anyone back from the dead but only those who were snapped by Thanos. This suggests true resurrections are off-bounds even to the most powerful beings in the MCU.

It also makes sense for the MCU to avoid easy resurrections. Gamora and Loki will still appear in future movies and shows, but both of them come from a different timeline — the original ones are unmistakably dead. Therefore, Vision can be reactivated and Pietro — now being played by a different actor — might come from another universe altogether, meaning the Quicksilver seen in Avengers: Age of Ultron remains dead. If the MCU completely dismissed death, however, any hero or villain could return at any given moment, stripping future stories of believable high stakes. It's unknown whether Vision and Quicksilver could live outside of Westview, but thankfully, future WandaVision episodes will shine a light on this issue.

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