The Doctor--the Metacrisis Doctor--was wandering about the halls of the TARDIS, doing his best for the moment to ignore the comm system and try to think. He wasn't making much progress. None of his other selves had the slightest idea what was going on, and he had to admit that he felt a bit trapped being only part Time Lord now. Part of him wondered if that was interfering at all with his ability to suss out the problem that was affecting the TARDIS.
He was so distracted by his thoughts that he completely missed the other person standing in the hall, and before he even registered that he was about to run into her ... he did.