Dragons at That Awkward Age

A reluctant, aging assassin. An angry dragon hitting puberty. A realm about to go up in flames...
Bib the sorcerer fears his marriage is on the rocks. But while the cynical forty-something and his wife attempt to restore her magically erased memories, a powerful magician enspells him with a command to kill a king. And while he wracks his brain for a loophole to avoid committing regicide, a ravenous teenage dragon shows up demanding answers.
Using the flame-throwing beast to prop up his waning physical prowess, Bib reluctantly slays the local ruler... and then hunts down the man who forced him into the deed. But traveling across the land with an acne-ridden sidekick has his past life flashing before his eyes in a worrying stream of questionably selfish decisions.