Gerard enslaved Julia in 1995, but he's making no move to do so now. Instead he apparently has his sights fixed on Elizabeth. He must have been listening to conversations and heard Barnabas's and Julia's story, but does he actually believe that they have been to a future where he was triumphant? If he nabbed Julia, he could nip her and Barnabas's investigation in the bud, and since he apparently has not yet reached his goal, it would surely be prudent of him to eliminate her as an enemy. But maybe at this point he doesn't have the power to nab anybody he pleases, and Elizabeth looks like a better tool than Julia.
Meanwhile, Julia is serving as a psychic instrument: she feels Gerard's presence when he is around. We don't have to see him as long as Julia's around to tell us he's there. But we see him anyway, bathed in green light, as if James Storm's sneer weren't enough to tell us he's bad news. If this continues, could they dispense with Storm altogether and make do with the green light and with Julia shivering?
It was very foolish of Elizabeth to go to that room after being warned against it, but why does it make a difference? Others have been all captured on turf that was not specifically Gerard's or Daphne's, so why shouldn't Elizabeth be?
