The CW is welcoming the Arrowverse's Batwoman, Ruby Rose, with open arms on social media. The John Wick: Chapter 2 and Orange is the New Black actress was announced as The CW's Batwoman and will make her debut in the annual Arrowverse crossover in December 2018.
Making a change from previous years, the upcoming Arrowverse won't include all four shows, Legends of Tomorrow is excluded. This is, presumably, to give more time to introduce Ruby Rose's Batwoman and her hometown of Gotham City. The plan isn't just for Batwoman to be a special guest star, but to launch her own TV series, set in the same universe as Arrow and The Flash. It's obviously very early but the support for Batwoman to be the next major hero of the Arrowverse is there with the show's potential network, The CW.
It was the official Twitter account for Arrow that first welcomed Ruby Rose to the TV multiverse with an image of the actress and Batwoman side-by-side. The post was later retweeted by the official show account for The Flash. Interestingly, the accounts for Supergirl and Legends of Tomorrow haven't tweeted anything about Ruby Rose's casting (yet).
On a pure surface level, there's nothing too surprising or illuminating about The Flash and Arrow being the only official show accounts to welcome Ruby Rose / Batwoman to The CW. The Arrowverse does bear Arrow's name, and that show is considered to be the flagship series. The Flash, meanwhile, has some of the best ratings for any CW show. It's natural that The CW would use the audiences of both shows to promote the new arrival of Batwoman for just those reasons. However, if things are taken in a more speculative (and hypothetical) route, the tweets could mean much more than just a simple welcoming.
Even though Batwoman will be apart of the Arrowverse, it's unclear on which Earth she'll land. Since Supergirl joined the Arrowverse, the various series have been confirmed to take place in a multiverse spanning several Earths and dimensions. Supergirl takes place on Earth-38 and Arrow is on Earth-1. In other words, Batwoman doesn't need to be on the same planet as Oliver Queen and Barry Allen to be apart of the Arrowverse. That being said, Arrow and The Flash accounts choosing to promote Ruby Rose could be a sign that Batwoman's Gotham will be on the same plane of existence as Arrow's Star City and The Flash's Central City. This would make the most sense too. Supergirl only exists on a different Earth than Arrow and The Flash because the series began its life on CBS, not The CW. In addition, Gotham would fit right alongside the look and feel of the other cities in the Arrowverse's Earth-1. Again this all (heavy) speculation.
The only thing that is truly clear is that The CW is excited about Ruby Rose being cast as Batwoman. It might not be enough to assuage some fan fears that the Australian actress (who is also a model and recording artist) is too young and relatively inexperienced to lead her own TV series, but it's a vote of confidence. The CW is chugging full steam ahead with Ruby Rose as Batwoman, no matter which Earth she'll call home.