SPOILER WARNING: This article contains major spoilers for "Battles Won and Lost," the Season 3 finale of Supergirl.
The Legion of Super-Heroes just gained a new member. In "Battles Won and Lost," the Season 3 finale of Supergirl, Winslow "Winn" Schott Jr. decided to join the Legion and travel to the future, leaving his friends and family behind.
In the finale, the Legion returned to the present just in time to save National City from the Dark Kryptonians' attempt to terraform Earth. When Saturn Girl and Brainiac-5 reunited with the DEO, though, they came bearing bad news. Despite the defeat of Pestilence, the future was in trouble -- from none other than the original Brainiac, who unleashed a virus that wiped out all A.I. apart from himself.
As such, Brainy opted to stay in the past and offered Winn his place on the Legion. According to Brainy, Winn was the only person with the knowhow to stop Brainiac once and for all. Brainy also revealed that Winn was the architect of the future's greatest technological advances.
Though Winn was reluctant at first, he ultimately decided to take Brainy's opportunity. After a major sendoff from the DEO, Winn joined Mon-El and Saturn Girl on their trip back to the 31st century. These circumstances explain why Jeremy Jordan, who plays Winn, has been demoted to a recurring character for Season 4. Jesse Rath's Brainiac-5, on the other hand, will be a series regular starting this fall.
Returning to The CW this fall, Supergirl stars Melissa Benoist as the Girl of Steel, David Harewood as Martian Manhunter, Mehcad Brooks as Jimmy Olsen, Chyler Leigh as Alex Danvers and Jeremy Jordan as Winn Schott, with appearances by Calista Flockhart as Cat Grant and Tyler Hoechlin as Superman.