Fans were rightfully upset when Katie Cassidy’s Laurel Lance was killed off in Arrow Season 4, but she soon resurrected on The Flash in an Earth-2 version of herself called Black Siren. Now, Cassidy is the latest member of the Arrow–verse to sign a deal across the network’s super-powered shows, following Wentworth Miller‘s deal (as Captain Cold) as well as John Barrowman‘s (as Malcolm Merlyn), both of whom will be appearing on Legends of Tomorrow as part of the new Legion of Doom villain team-up.
Miller’s character Captain Cold sacrificed himself late in Legends of Tomorrow’s first season, but we saw later that he was still alive, of course, in the past. And since Legends and The Flash engage in a lot of time travel, seeing past cast members appear isn’t a big surprise. So will Sara (Caity Lotz) go back in time and visit her sister in the past on Legends of Tomorrow, or will the villainous Black Siren from Earth-2 somehow end up with the Legion of Doom? (Whose members also include Matt Letscher as Reveres-Flash / Eobard Thawne, and Neal McDonough as Damien Darhk).
According to TV Line, Cassidy will be appearing the first episode of Arrow Season 5, so that might give us a better idea of how she might be used in the series. It’s also interesting to note that none of the deals include Supergirl, which recently moved over to the network from CBS. In The Flash Season 2, it was established that Supergirl exists in an alternate reality, which makes crossovers a little difficult. But there has been talk that the Berlanti-verse will be doing full crossovers of all four shows, though it’s dizzying to think how.