I hung out with Dennis at various conferences and had various emails with
him over the year. He was usually quiet but did have a wry sense of
humor.
Mostly at the conferences, he was content to hang out with us in the lobby
or wherever. If you didn't know who he was, he looked just like the rest
of the UNIX geeks.
He was very caring, and I got a condolence email on the passing of a
colleague. The most unexpected one was that back in the day on one of the
mailing lists, I think it was INFO-MICRO and not UNIX-WIZARDS, someone was
talking about since Andrew Fluegelman had died recently and he is generally
credited with the idea of shareware, that it be renamed fluegelwaer in his
honor. In my rebuttal I suggested that we rename the C compiler Ritchie.
I got a quick "Let's nip this in the bud right now" letter from Dennis.
One year while working for the Army I made up a bunch of No Ada t=-shirts
and sold them at one of the conferences. I gave Dennis one and I always
got a chuckle when I saw pictures of him wearing it later. If you have
Peter Salus's UNIX history book, there's a picture of him wearing it there.