The introduction of the Legion of Super-Heroes has been a significant part of Supergirl's story this season. Not only did it finally bring the classic comic book team into the Arrowverse, but it also brought Mon-El (Chris Woods) back to National City and offered up much-needed help in Supergirl's (Melissa Benoist) fight against Reign.
With the Legion being from the future, Team Supergirl already knows that Reign will eventually disappear or be defeated, and hints that the Legion played no part in her defeat. But Imra Ardeen/Saturn Girl (Amy Jackson) is able to persuade Mon-El to get the team involved while Supergirl is in a coma, potentially changing the future. Is it possible that, by getting involved with the fight against Reign, the Legion of Super-Heroes is setting Supergirl up for a timeline reset?
It's an interesting theory, and one that may have some merit. For starters, Mon-El has been seen in a promo for upcoming episodes of The CW series wearing a costume that is far closer to his traditional comics costume than the black leather jumpsuit he and the rest of the Legionnaires have appeared in on the show. Some theorized that this change in costume could be due to the Legion's involvement changing the future. The changes would be subtle and not change the fact that they still end up in National City in the 21st century, but might change the reason, the purpose, and even the makeup of the team.
It also would provide a possible opening for the twist that Jackson revealed in a recent interview with Entertainment Weekly would have a major impact to the show's plot this season.
“In the next episodes, more will unravel,” Jackson revealed. “Obviously, I can’t reveal too much, but there is a twist and the turn in the plot for sure.”
While Mon-El's rationale for not involving the Legion with the fight against Reign was centered around keeping the team from dying and losing the information they needed to fight something called the Blight in the future, it's likely he didn't consider that even if they survived it would still impact the future. After all, the Legion did reveal that most of mankind's history was lost. The team fighting Reign might just be enough to change everything in the future, leading to Mon-El and Imra's marriage to either never have happened at all or to simply end.
Whatever the details, it's likely that the Legion's appearance will have some impact on the future. Fans will just have to wait and see how that plays out as Supergirl continues.
Supergirl airs Mondays at 8/7c on The CW.