Tana is the friendship/romantic pairing of Tom Okanawe and Jana (Vilkas). It begun in Series 2. They are good friends, but it is shown that Tom may have a crush on her. This is shown in the second series in the episode Dances with Wolfblood where Tom puts his arm around Jana, and also playfully growls at her in the same episode ( dances with wolfbloods at the start).
Also in Top Dog, Jana grabs Tom's arm, meaning she is trusting Tom more and it is a friendly gesture.