Supergirl‘s latest addition will have you feeling blue — in the best way possible.

Jesse Rath, introduced earlier this year as Brainiac-5 (aka “Brainy”), will be a series regular when the CW drama returns for its fourth season, TVLine has learned.

“We love the character of Brainiac-5 and can’t imagine anyone but Jesse Rath in the role,” executive producers Robert Rovner and Jessica Queller said in a statement. “He brings such fun, heart and brilliance to Brainy, and we’re so excited he’s joining the cast as a series regular for season 4. We have a lot of great Brainy stories to tell.”

Rath made his first appearance in the 10th episode of Season 3 when Brainy entered Kara’s coma dream after her first scuffle with Reign. Brainy recently returned to the future with fellow Legionnaire Imra, but as revealed in the trailer for Monday’s season finale (8/7c), he’ll be back in a big way.

Your thoughts on Rath’s promotion? Hit PLAY on the finale trailer below, then drop ’em in a comment.