Fritz Pearlmutter backstory

Forgive me if this topic has already been exhausted. New to this subreddit, but not the series.

Something that I've always wondered about is why Ward doesn't do sub series regarding the doggen? But specifically Fritz.

Just saying, I would love a good backstory novel about him, maybe about his childhood (if he had one), how he progressed through his training to be a good doggen (if there was any). All of it leading up to him serving Darius and how he meets him.

Apologies again if this material has already been covered. So far all I can remember is that we get snippets of information, but that's about it. I'd also like Ward to explore if it's possible for a doggen to rebel against their nature? Like how Murhder's old doggen (mentioned only once, and not in his story but in John's story) was so dour and gloomy...was that because he hated his master? Or hated his position? Or just hated that being a doggen was his lot in life?

And let's not forget it was a doggen who snitched on the location of Wrath's family home to the lessers. Probably under torture, yes, but still....am I just expecting too much out of a smut series?