She felt that there is a "different kind of energy" between Rose and the Tenth Doctor, whilst Tennant remarked that the audience would get to see the Doctor-companion relationship "developing and becoming something that it maybe hasn't before." Piper stated that with the Tenth Doctor, Rose is "more tetchy and more possessive" over him as "she feels like she's lost him once and doesn't want to lose him again". She cited Rose's "catfight" with former companion Sarah Jane Smith in "School Reunion" as evidence of this. Discussing the possibility of Rose and the Tenth Doctor becoming more romantically involved Piper stated "You want it to happen, but at the same time you don't want it to happen". Tennant likened the dynamic between the pair to that of Dana Scully (Gillian Anderson) and Fox Mulder (David Duchovny) in The X-Files. Both Tennant and Piper agreed that the expectation of the relationship is more exciting than having it realised. To add to the tragedy of their separation, Davies scripted the series two story arc so that Rose and the Doctor would be indirectly responsible for their separation. "It's deliberate when that happens [the Doctor and Rose's arrogance]", said Davies, "and they do pay the price. In "Tooth and Claw", they set up the very thing — Torchwood — that separates them in the end. It's sort of their own fault." Though Davies left the Doctor's response to Rose's declaration of love in "Doomsday" unstated, Gardner felt strongly that the character reciprocated her feelings. On the commentary for the episode she stated that she would "confirm to the world" that he was going to "say it back." Davies created the expectation of Rose's return in the fourth series by mentioning her in dialogue and featuring Piper in cameo appearances in "Partners in Crime", "The Poison Sky", and "Midnight". Speaking on how Rose's character had changed between her appearances, Davies described the fourth series Rose as "tougher, more independent, and [she] might, at times, seem a little harder". Piper stated she rewatched her earlier episodes to remember how the character spoke and acted as she felt she had "been playing posh birds" since she left the programme and by contrast "Rose is a bit of a chav". Rose is re-united with the Doctor near the climax of "The Stolen Earth". Director Graeme Harper insisted that the scene appear "mystical" because the characters' reunion was