MCU fans watched as Bruce Banner was no longer Smart Hulk after Shang-Chi and the Legend of the Ten Rings was released in theaters in 2021. However, that all gets reverted back, as Bruce Banner is once again Smart Hulk in the new MCU series She-Hulk. Bruce really puts forth the effort to be the scientist version of himself for as long as he can and not the Hulk version of himself, and it had appeared that he had done a really good job of that in the years that he was working on being Smart Hulk.
Even after doing all of the hard work to make himself feel like his old self again, it just was not enough and he decided to lose the Hulk altogether and just become regular Bruce again with no Hulk powers. Fans are wondering how Bruce Banner is back to being Smart Hulk in She-Hulk.
Why is Bruce Banner Smart Hulk in She-Hulk?
One of the most popular and interesting theories as to why Bruce Banner is all of a sudden back to being Smart Hulk is that the show takes place within the five year time jump that was the timeline between Infinity War and Endgame. Fans have not gotten a full explanation of what all happened within that time jump that occurred between the two movies, but this would make sense, as Bruce is trying to find a way to cope with what happened.
It would also make a lot of sense that his cousin, Jennifer Walters, was injured in some capacity that required her to get the transfusion from her cousin that made her into the She-Hulk character. This theory would make the most sense as it would account for Bruce still being Smart Hulk in Endgame, yet being his former self in Shang-Chi. Even though this theory seems the most likely, it would not explain the reasoning She-Hulk was not involved with or even mentioned in Endgame.
One would think that Bruce, being the new person that he is, would have been excited to introduce the other members of the Avengers to his cousin, who is just like him. Bruce could have just been trying to be a good guy, as everyone in the movie lost many members of their life, and it would not be fair for Bruce to be bragging about still having a family member. Either way, this would not be the first time Marvel went out of time order when telling stories.