[gmw]

Thanks for your thoughts, Dr. Drib. Like dialogue, characters thoughts are not always as clearly stated as they could be, but your interpretation of my original sentence does have me concerned about how unclear it must be. You appear to be making a connection between the two clauses that was not intended.

The person, let's call him Carl, is lonely and thinking of his two best friends, but their separation from him are independent events. Abby has just departed from Carl - which is how Carl comes to be sitting there feeling sorry for himself. Bill left a long time earlier, but regular messages had kept Carl informed about where Bill was, however, the most recent message said that Bill was travelling further north and that Carl might not hear from him for a long time. They come together into a single sentence/thought, not because the events are related, but because they are his best friends and he misses them both.

So an alternative phrasing might look something like:

Abby was gone, and Carl no longer had any idea where Bill was.

I realised after I posted that my original sentence used "knew" rather than "knows" (I think I confused myself by trying to be clever in the subject).

Abby was gone, and Bill was who-knew-where now.

Perhaps even dropping the "now" would help, it's probably unnecessary (and perhaps the cause of the confusion).

Abby was gone, and Bill was who-knew-where.

Not that I am emotionally attached to "who knew where". It's just the phrase that seemed to fit the situation and character at the time I wrote I scene, but I couldn't work out how it should be punctuated.