Even my first experience as a Pup, while grounded in and built around the world of Human Puppy Play; it still included elements from the BDSM & Leather Kink and Fetish world as a part of that… and it wouldn’t stop there.
No seriously… fuck ALL of that noise. The self expression of oneself as a Human Puppy is limited only by that same individuals own self identification and imagination. There is literally no reasonable manner in which someone else may decide if or in what manner another may identify as such.
There are all kinds of Human Puppy relationships, and no two are the same. Pup Brothers, similarly, come in all shapes and sizes with their own unique interactions.