So, anyone who watched some of the Fl4k streamer gameplay the last couple days or so may have noticed something kinda huge: Tannis speaks to the Vault Hunter in direct-brain-injection Siren-style after you recover a vault key fragment. (Side note: BALEX is f***ing awesome.)
Thoughts? Any connection (I think very likely) to the Sirentology side mission in the Fight For Sanctuary DLC which seemed to drop a few hints and bits of foreshadowing?
And of course, there was that Battleborn easter egg: TANNIS IS NOT WHAT SHE SEEMS