I have an AU where Borys (BLU Heavy OC) is a werewolf and knotted on Fritz to give him his pups, which were twins. And in this AU I based it lightly on Wolf Children where the pups were born as... Pups, but as they grew older they one day shifted to toddlers.

Either way yes to all that!! If being pregnant was foreign enough, being pregnant with puppies is so much more otherwordly to Fritz. However (either religious guilt or mindbreak) he ends up caring for the litter, rubbing his belly tenderly and cooing to the pups. He ends up giving birth to a litter of around 5-6 black pelted puppies that whine and crawl all over his chest to get milkies.