User blog comment:PhantomBlade404/Dragon Priest and Word of Power of Volskygge/@comment-3492791-20120903003548

Volsung is scripted to burst out when you learn the word. It is possible that you had already been there, learned the word, then ran like hell when you say a dragon priest show up behind you. This would mean that, without the word to activate the scripted sequence, Volsung can no longer spawn.