Alex will follow right away but Billie will walk over to Darren and when he looks up at her she'll just chuckle, "You're still pathetic." 
Then she'll follow and she will look at Rose and Zach. "You alright Rose?" She'll ask.

[S]I sibling ship them. I see Zach and her like Alex and Billie. [/S]

Yeah... it will be bad for a while with the demon crowd. And Alex will sit there like, "I told you guys, allowing Darren to take back over was a bad idea..."
"It's fine Al, we have our own to protect." Billie won't go bad to leading unless it was dire... like they started getting killed.