SPOILER WARNING: This article contains major spoilers for "Triggers," the latest episode of Supergirl.
Miss Martian has returned to National City -- sort of. In "Triggers," the latest episode of Supergirl, the White Martian-turned-hero reached out to J'onn J'onzz psychically with an urgent message: he must go to Mars. M'gann M'orzz appeared to J'onn at the alien dive bar where she once worked as a bartender. As he enjoyed a drink, M'gann appeared before him and wrapped her hand around his. "J'onn, you must come to Mars," she said. "Now." She then vanished as suddenly she had appeared, leaving J'onn too stunned to respond.
While it's unclear whether M'gann will play a role in Season 3, we know one Martian who will: Carl Lumbly's M’yrnn J’onzz, the father of J’onn J’onnz. Lumbly's casting was announced this summer at Comic-Con International in San Diego.
The character is described as "a pacifist religious leader on Mars" who "M’yrn pushes his son in unexpected ways." In her brief appearance, M'gann never mentioned M’yrnn, but it's very likely that he is one of the reasons she wants J'onn to return to Mars. So far as we know, J'onn believes that his entire family has died at the hands of White Martians, so this may come as something of a shock to him.
M'gann left Earth in Season 2 in order to stop the White Martian's genocide of the Green Martians. Before she returned to Mars, she and J'onn developed romantic feelings for one another, though these feelings weren't explored in any great depth. She was last seen in the final episodes of Season 2, where she worked with other White Martians who are Green Martian sympathizers in order to stop the Daxamite invasion of Earth. Because she is a White Martian, M’yrnn may very well hold a grudge against M'gann for the crimes of her people, making it difficult or impossible for these two rebel Martian factions to work together.
It is unclear at this time what M'gann's message means for J'onn. J'onn is a series regular character, so -- if he does return to Mars -- it's unlikely that he will stay there for long. However, his return could also set him a family reunion with his father M’yrnn.
Airing Mondays at 8 p.m. ET/PT on The CW, 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.