When it comes to time travel stories, a few rules seem to be universal. Many different stories about time travelers explain that they cannot change the past without altering the future, otherwise known as the butterfly effect (this is the reason most time travel stories do not include characters actually killing Hitler or stopping the Kennedy assassination). Many of them also involve the concept of being careful not to create a paradox, such as by meeting your past or future self. While the stories are different, the rules tend to largely stay the same.
On Legends of Tomorrow, the rules exist but seem to be a little fuzzier. Several characters have interacted with their past selves, none more that Martin Stein who has had multiple conversations with his younger self. As for changing the timeline, they'll sometimes let the small things slide as long as history remains intact. However, that's soon going to catch up with the.
The synopsis for the season finale 'Aruba' has been released, and it looks like the Legends are going to to be forced to break one of the rules of time travel:
“Aruba” — (8:00-9:00 p.m. ET) (Content Rating TBD) (HDTV) SEASON FINALE — As the Legends are about to take off for their next destination, a massive timequake rocks the ship. In order to try and fix what has happened, they are forced to break the one cardinal rule of time travel. But if they are able to destroy the spear, they will face the ultimate consequence. Victor Garber, Brandon Routh, Arthur Darvill, Caity Lotz, Dominic Purcell, Franz Drameh, Nick Zano and Maisie Richardson-Sellers. Rob Seidenglanz directed the episode written by Phil Klemmer & Marc Guggenheim (#217). Original airdate 4/4/2017.”
A few weeks ago, executive producer Marc Guggenheim revealed who some of the characters appearing in the finale would be, including The Legion of Doom, Captain Cold, Laurel Lance, and J.R.R. Tolkien. Since the promo and synopsis for the upcoming episode ‘Fellowship of the Spear’ include both Captain Cold and Tolkien, it seems likely that 'Aruba' is going to be heavily set up there.
Before getting to 'Aruba', however, the Legends will have to deal with ‘Doomworld’ when the Legion of Doom changes reality with the spear. Whether the ramifications from that are also affecting the events in 'Aruba' remains to be seen. But actions have consequences - the Legion will learn that once they use the spear - and it sounds like the Legends will also be forced to face the consequences of the choices they make to destroy the spear and save reality.
Legends of Tomorrow continues Tuesday, March 21 with ‘Fellowship of the Spear’ at 9 pm on The CW.