 Adam Mitchell joins the Doctor and Rose in the episode " Dalek " . The character was first conceived during Russell T Davies ' 2003 pitch to the BBC : it was always the intention for Adam to join the TARDIS team after Rose developed a liking for him . Contrasting against Rose , Adam was created to show that not everybody is suited to be a companion . Davies stated that he " always wanted to do a show with someone who was a rubbish companion " and dubbed Adam " the companion that couldn 't " . Upon returning Adam home , the Doctor informs him that " I only take the best . I 've got Rose " . Fraser McAlpine , reviewing Adam 's appearances as companion for BBC America 's Anglophenia blog , described Adam as fulfilling a role as " the companion that proves the worth of all of the other companions " . From episodes nine through thirteen , Rose and the Doctor are joined by the con man Jack Harkness . Jack 's appearances were conceived with the intention of forming a character arc in which Jack is transformed from a coward to a hero . John Barrowman , reflecting on the interrelationships between The Doctor , Jack and Rose , felt that " the subtle sexual chemistry between all three characters ... was always in play " with the caveat that " the relationships were by no means driven by desire " . SFX magazine also commented on the " intoxicatingly flirtatious dynamic " and compared the trio to " a Buffy @-@ style Scooby gang who can quip in the face of danger " . Jack parts from the Ninth Doctor with a kiss which Barrowman felt to be " full of fondess and respect " and both " a significant moment in the annals of the series " and " a moment full of melancholy and loss for the characters " . 
