A younger version of The Orville's Commander Kelly Grayson had a chance to prevent the Kaylon from launching a full-scale attack on the universe. And yet, one minor moment stopped her from preventing the worst timeline ever seen in the sci-fi series.
The Orville was created by Seth MacFarlane and is a loving tribute to classic science-fiction, most notably Star Trek: The Original Series and Star Trek: The Next Generation. The show has dabbled with a number of genre-appropriate tropes, including time travel and diverging timelines. In the episode "Tomorrow, and Tomorrow, and Tomorrow," a younger version of the USS Orville's Kelly Grayson comes onboard after a scientific mishap brings her seven years into the future. Before sending her back to the past, Dr. Finn memory-wipes Kelly in order to protect the timeline. But, unfortunately, it doesn't take and Kelly inadvertently changes history by declining a second date with her future husband, Captain Ed Mercer.
And while Kelly has knowledge of Kaylon orchestrating an attack, she doesn't appear to warn anyone about the war the Union is heading towards. The tie-in comic The Orville: Digressions by David A. Goodman and David Cabeza showcases the alternate timeline explored in the Orville’s season 2 finale. After returning home and moving on with her life, Kelly's journey to the future slowly turned into a distant memory. In fact, it isn't until her current ship, the USS Jefferson makes a call to the Orville that Kelly sees Isaac onboard, and remembers he and the Kaylon are going to betray the Union and launch a full-scale war. She discusses her memory with her husband Cassius, who convinces her that this is a different timeline and the Kaylon may not actually attack.
However, Kelly realizes the Kaylon’s attack is still set to happen once she meets the Orville’s Chief Medical Officer, Claire Finn. Only in this timeline, Finn never worked onboard the Orville and thus never formed the relationship that would cause Isaac to turn his back on his people and help the Union survive the Kaylon’s onslaught. By allowing herself to believe that "the universe will take care of itself," as Cassius told her, Kelly almost condemned all life to the Kaylon's vicious onslaught. While the USS Orville is full of proactive people, Kelly Grayson has proven herself to be one of the ship’s most responsible members. But the Kelly plucked out of The Orville’s original timeline was younger and couldn’t comprehend the ramifications of her actions. She was willing to believe what Cassius told her because it reassured her that her decision to change the timeline was OK. But her meeting with Dr. Finn showed Kelly that it wasn't the universe's responsibility to take care of itself.
Kelly did own up to her actions and tried to rectify her mistake, but it was too little, too late. Thankfully, the show reveals that Kelly and the rest of the Orville crew were able to undo the incident and save the universe from the Kaylon.