Just a friend. One I've fought alongside with here. I trust him, if that's what you mean. His name's Jim Kirk, and he's just brilliant. I think you're gonna love him.

[Or really, she wants the Doctor to adore him and think he's brilliant, but she's going out on a limb here to guess that won't be the case.]

And before you think anything of all that, don't. He's just a mate, not -

[The words anything like you die before they make it out between them. But it's entirely obvious by the look on her face what she's trying to say.]

It's just not like that.