Glitch report, maybe this is fixed and it doesn't actually affect anything, but trying to defeat the slavers in the third area before Badon resulted in Metatron's pic showing in the background. She didn't join the bad guys, just her picture was there, and didn't go away until I talked to her at camp.
One thing I do like about returning to earlier areas is you might run across a couple of teammates. I've seen Sarah and Ashley, and Sam and Ashley so far, and it's neat seeing others training too.