Why are unicode characters not rendering correctly

I am not entirely certain what the cause of the problem is, but the steps below might help:

1. Confirm that the locale is set up properly

   $ locale
   LANG=en_US.UTF-8
   LC_CTYPE="en_US.UTF-8"
   LC_NUMERIC="en_US.UTF-8"
   LC_TIME="en_US.UTF-8"
   LC_COLLATE="en_US.UTF-8"
   LC_MONETARY="en_US.UTF-8"
   LC_MESSAGES="en_US.UTF-8"
   LC_PAPER="en_US.UTF-8"
   LC_NAME="en_US.UTF-8"
   LC_ADDRESS="en_US.UTF-8"
   LC_TELEPHONE="en_US.UTF-8"
   LC_MEASUREMENT="en_US.UTF-8"
   LC_IDENTIFICATION="en_US.UTF-8"
   LC_ALL=en_US.UTF-8
   

2. Enable the desired locales in /etc/locale.gen and run locale-gen

   $ cat /etc/locale.gen |grep UTF
   en_US.UTF-8 UTF-8
   nb_NO.UTF-8 UTF-8
   ru_RU.UTF-8 UTF-8
   

3. Make sure that the desired font can be loaded

   $ xset +fp /usr/share/fonts/cyrillic
   $ fc-cache
   $ fc-list # to check
   

4. Apply the settings from .Xdefaults (or similar) before starting the "first terminal"

   xrdb ~/.Xdefaults