Gwen

(S02E06) "Let's say we were under the same Doctor." Martha Jones explaining to Owen how she knows Jack.

This was probably the most anticipated episode of the season for die-hard Doctor Who fans. It marked the arrival of The Doctor's most recent companion, Martha Jones, for an extended run on the series. As fans of that series know, Jack met up with Martha during his most recent bout with The Doctor on Doctor Who. At the end of that show's fourth season, Martha made the decision to leave The Doctor and stay behind on Earth. As such, it makes perfect sense that she would be available now to appear on the spin-off. And she fit in pretty seamlessly with the gang, even serving to lighten up Jack a lot.

(S02E04) When Gwen first joined Torchwood, she brought with her an element that none of the other team-members had, namely a significant other in Rhys. Since that time she has struggled to keep those two worlds separate, insisting to Rhys that she was still working for the police department and keeping him in the dark as to the otherworldly doings of Torchwood. Seems that would be difficult to maintain, right? Well, Cardiff is only so big so inevitably it would become impossible.

(S02E03) The adventure starts in 1918, featuring the Torchwood of its era. We get to see the future from the perspective of the past and the end of the episode from the perspective of the beginning. Confusing? Good. It's time travel, you're supposed to be confused. Torchwood continue its string of excellent episodes this run with this Tosh-centric installment. The inner struggles between team members seem to be a thing of the past, resolved while Jack was away, and what we have now is a real solid force that I can believe is prepared for whatever is coming.