It shouldn't really be a surprise to see Kirk in here, but somehow Kirk's appearance catches him unprepared.
So he's a little guarded too, even as he takes the offered coffee with a smile. "Well, as long as you keep bringing me coffee, how can I refuse!" he teases lightly, and then realises: "Actually, the whole thing with Ianto started with him bringing me coffee." He lifts an eyebrow, lips twisting wryly. "You're not trying to seduce me to hide the fact you want to hide your dangerous Cyberman girlfriend in my basement, are you?"