[The Doctor is the most awkward he has ever been in the company of Jack and Rose. There used to be all sorts of talk of flirting when the three of them traveled together, but that was another time, another Doctor. Flirting had been safe, because who could have seen the ninth him ever settling down with someone, or at least as near to settling down as he ever got? Now, with his feelings for Rose all but put into words, flirting is so much more dangerous.]
Yes, yes, you'll have to ... Wait. Join her how? [The Doctor darted a look between Rose and Jack, his eyes widening.] Oh no. No no no. If anyone's sleeping with Jack, it'll be me.
[He winced a moment later, realizing exactly how that statement had sounded.]