Supergirl has been firing on all cylinders this season. A move of networks and locales hasn't diminished the show at all, and thanks to an experienced stunt team borrowed from the rest of the Arrow-verse, the action's improved tremendously. But you know what would kick Supergirl up a notch before the inevitable Crisis that will bring it in line with the rest of CW's super shows? Batwoman.
After the announcement that she's getting her own solo book again, DC's flagship lesbian is due for her own live-action interpretation, and the world would be a better place if that interpretation was found on Supergirl instead of Gotham or the DC Cinematic Martha-verse. Not that Batwoman wouldn't be interesting if found in those other universes — after all, the Dark Knight's right-hand woman/cousin would definitely be a character who would still have red hair and punch bad guys.
But Supergirl has actually built up a world that Kate Kane would naturally fit into — and there are even references to prove it. The biggest one is of course Maggie Sawyer, the National City detective that set Supergirl's sister Alex on her path to sexual awakening. Beginning in the 2011 DC comics reboot, Maggie Sawyer was a romantic foil for the Batwoman/Kate Kane, first as her girlfriend and later as her fiancée. They broke up only after DC refused to let them marry and because Maggie's ex wasn't crazy about their daughter sharing a loft with Batwoman's very gay party girl alter-ego.
Obviously, that break-up is unlikely to ever be a part of Supergirl canon as Sawyer has appeared in six episodes thus far with no offspring in sight. But that's fine because Supergirl's Maggie Sawyer is Maggie Sawyer in name only. The character much more closely resembles another Batwoman paramour — Renee Montoya.
Renee and Kate's relationship dates back to the reintroduction of Batwoman in 2006. The two were on-again-off-again until the 2011 reboot when Renee disappeared and Kate found romance with Maggie. But Montoya and Supergirl's Sawyer have a lot in common — first of all, there's the physical resemblance:
Second of all, they're both women of colour who have been out a while, though Sawyer appears to be out at work while Montoya's comfort in the closet was a major plot point in Gotham Central. Both are also a little reserved, playing things close to the vest.
But unlike Supergirl's Maggie Sawyer, Renee Montoya was always a fully fleshed-out character. Maggie has been a (delightful) romantic interest, but not really a character. An ex who happens to be a superhero would give the character some definition beyond "nice smile" and "gay".
And Batwoman would absolutely liven up Supergirl's own plotline, too, which has languished since Calista Flockhart left at the beginning of the season. Trucking in another female superhero to serve as foil and mentor (or partner) might be the shot in the arm her story needs, and would address the issue with the male characters having most of the major storylines this season.
And it's not like there haven't been references to a bat in Supergirl's belfry before. There's a mention of Gotham City in the very first episode of season two, and in episode six of season two Kara mentioned a gadget-obsessed vigilante her cousin teamed up with once. Pointedly she made no mention of gender.
There's a fundamental law to nearly all Super-stories: If a Superperson exists, so does a Batperson. Wherever there is an exuberant alien with bulletproof skin and the need to see the best in humanity, there is also a rich kid who never quite got over a tragedy and likes to put on bat ears at night. They go together like peanut butter and jelly.
Get on it, Supergirl. And then feel free to get to work on the Batwoman spin-off series.