Supergirl has enlisted one ofThis is Us' flashback tykes for a big episode about aspiring hero James Olsen.

TVLine has learned that Lonnie Chavis aka Young Randall on NBC's freshman hit will guest-star on the CW superhero series as Marcus, a young alien boy who bonds with James (played by Mehcad Brooks) after the rugrat's mother attacks National City.

The episode, titled "City of Lost Children" and airing Monday, May 8, promises to find CatCo's interim CEO at a crossroads, as he grapples with his extracurricular destiny.

"There's a lovely moment that I have with Mehcad, about accepting who you are," shares David Harewood, who plays DEO boss man Hank Henshaw aka "Martian Manhunter" J'onn J'onzz. "James is reluctant to step in and help somebody, and I persuade him, as a hero, that sometimes you have to go against your own instincts and do something that's right, as opposed to what you think might be right."

In success, might National City's Guardian eventually suit up for Hank & Co.? "I really want to see James in the DEO," Harewood says. "Winn has been a real find in the DEO, so maybe one day we can get James in there, as well."

Supergirl resumes Season 2 on Monday, April 24 at 8/7c, with the Lena/Kara-centric episode "Ace Reporter."

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