The fourth episode of What If…? explored the dark and tragic story of what would have happened to Doctor Strange if, instead of losing his hands in his car accident, he lost his love, Christine Palmer, instead. The episode was well-received for several reasons including its emotional depth. But the episode was also crucial in introducing more lore around potential multiversal connections and how variations in timelines work.

Obviously, we first got a taste of this in the Loki series when we got introduced to the so-called Nexus Events that marked the beginning of a new timeline. In the Doctor Strange episode, the Ancient One tells him that Christine’s death was an “absolute point” in time that needed to happen in order for him to start on his journey. Changing it through magic he only gained as a result of this incident leads to a paradox. Well, What If…?‘s head writer, AC Bradley, clarified in an interview that:
I should have called it a Nexus point instead of an absolute point, but the Loki scripts weren’t even written yet.
AC Bradley
Considering the What If…? episode script was apparently written in February 2019, it makes sense that all of the future multiversal languages that the MCU ended up using would not have been universally used in other projects so far out. But the confirmation that Christine’s death was a Nexus Point connects the franchise with Loki and the event that created the multiverse. We’re currently exploring the aftermath of that very moment. It also gives us our first look at a Nexus Point occurring in one of the many timelines and how exactly it works. As Doctor Strange can tell you, it’s not all that easy or safe to find a loophole around one.
Source: YouTube