I think all the other characters are fictional on his Earth. Pretty sure BL is not part of either the Arrowverse or Supergirl's world. They could still do a crossover by having him go to one of theirs or them going to his.
The Vixen reference in today's episode pretty much locks it in the Arrowverse. The way it was said implied Vixen is a person in their world, Vixen isn't known in the Supergirl universe. The Supergirl reference in this episode does as well, as you have to remember that Supergirl is known in the Arrowverse also because she and the rest were given public recognition by the Government after they stopped an alien invasion.
Reply by XMinusOne
on February 11, 2018 at 1:42 AM
I think all the other characters are fictional on his Earth. Pretty sure BL is not part of either the Arrowverse or Supergirl's world. They could still do a crossover by having him go to one of theirs or them going to his.
Reply by Innovator
on March 21, 2018 at 3:06 PM
The Vixen reference in today's episode pretty much locks it in the Arrowverse. The way it was said implied Vixen is a person in their world, Vixen isn't known in the Supergirl universe. The Supergirl reference in this episode does as well, as you have to remember that Supergirl is known in the Arrowverse also because she and the rest were given public recognition by the Government after they stopped an alien invasion.
Reply by poweranimals
on March 24, 2018 at 11:16 AM
I guess it has to be Earth 1 then. I wish the writers would've just admitted it then instead of trying to be all like "It's not connected" BS.
Reply by rvcanuck
on March 28, 2018 at 9:32 AM
It could just be the basic DC universe. Which means Black Lightning and his kids could end up in the Justice League like in the comics.