R2-D2 and C-3PO are uniquely unifying throughlines throughout the entire Star Wars saga. Any similar throughline for the dark side just does not exist. What's more, a lot of folks who lived from one era to the next went from Galactic Republic to Empire (Yularen, Cody), not Separatist to Empire, let alone Separatist to Empire to First Order.
There could be some specific faction bridge characters, like Palpatine and Vader do between Empire and Sith, but there aren't really any timeless R2-likes who'd be viable for dark side.
Though for a good faction bridge that would put together a lot of good units, Grand Admiral Rae Sloane as a First Order/Empire bridge. And she'd make way more sense as a capital ship commander than
General Hux.
"leef;c-1550734" wrote:
So you're saying we need a LS thrawn aswell?
We have a light side Thrawn. That's Han Solo.