...it's like that for me and Annabeth, too. [He hasn't quite detailed this to people yet, but Barnham seems like he'd understand.] Our friends are counting on us. There's something only we can do back there and without all of us, it isn't going to work. Civilization's in danger if we don't put an end to the threats back home.

Maybe that's one of the common threads here. Bringing in people that could change their own worlds or something.