Tia and Cara both travel for their esper work, and like good partners with tricky backlashes, they go with each other so they can be on-hand for guiding and moral support.
This week, Tia has a case in Toronto that she's better suited for than Epione (the client is rich, and would rather fly out the esper with a much shorter list of requirements than give up their 'sensory bouquet', as they put it.)