That explains the weird conversations

There's a tall blond guy who sits most days in the linguistics library and studies. He always seems to be there, no matter what time of day. Now and then I see him in the tearoom too, making himself a drink. Sometimes I try to have a brief chat, though this seems to fluster him a little. Simple observations like, "You were working late last night," or questions like "Have you recovered from that cold you had last week?" often receive confused replies.

He seems very industrious: the student I wished I'd been as an undergraduate, doing extra readings, writing up his notes, reading multiple perspectives on each topic, preparing assiduously for tutorials. He arrives before me in the morning and leaves later at night.

Today I walked into the tearoom and did a double take. He was in there. Standing next to himself.

It turns out there are two of them, similar enough to pass for twins. Suddenly all is clear. (And he's only half as industrious as I had thought.)