Robert was an NPC that I first improvised during a D&D session. A PC had cast detect evil and good, and I wondered what the players would do if I told them that they did detect an undead presence under them (they were standing on the docks of a busy port).
The PCs felt for the guy (after they found a magical way to communicate with him) and ended up carrying his (mostly inanimate) bones with them for the rest of the campaign.
Now, I've given Robert the ability to move about on his own so he can continue his journies.