He seemed generous, broad-minded, and, for a sailor, very much of a man of the world.

It was easy for me to overlook his excessive suavity of speech and super-courtesy of social mannerism.

It was not that.

But all the time I was distressingly, and, I suppose, intuitively aware, though in the darkness I couldn't even see his eyes, that there, behind those eyes, inside that skull, was ambuscaded an alien personality that spied upon me, measured me, studied me, and that said one thing while it thought another thing.
When I said good night and went below it was with the feeling that I had been talking with the one half of some sort of a dual creature.

The other half had not spoken.