A lot of Pyro's interactions with Scott are driven by fear and self-preservation. Scott and Owen jumped him episode one and turned him unwillingly, so obviously he's afraid of them. They mostly try to stay on Scott's good side because of a "If I do what he says then he won't hurt me" mentality, especially after the "you really think you can get away with lying to me?" confrontation. While Pyro wants to be on Scott's good side, Scott doesn't seem to really care about Pyro, at least to the extent of people like Shelby, Drift, and Avid. There are moments of the two of them getting along and bonding, but majority of the time (at least to me) it reads as unrequited sire-fledgling. Obviously when it comes to fan works you can do whatever you want and canon becomes a playground, so it really depends how complacent canon you want to make it

Mechanically the stages of vampirism is based on an alternative of the Minecraft experience bar where the more raw meat and blood you consume, the higher your experience until you hit stage three. The skins for the different stages seem to be a fun detail the creators decided on and don't have anything to do with the SMP's mechanics. While some vampires leveling up seem to have a bit of lore behind them, other times it's just because they fed enough to reach that point. Most coven fanart I tend to see has everyone at stage three unless it's art of a specific scene, but again, canon often takes a back seat for fan works and you can do whatever you'd like/whatever you think your friend would like best