The extremely specific genre that stabs me right through the heart is tf where the transformee is being gently guided through what can very obviously be a very intense physical and emotional experience, especially by someone else who's gone through the same thing before themselves.
This can be presented in a sort of medical context, or a magical one, or something akin to how I write dragons turning into their true forms for the first time, or loving and gentle werecreature turning. Someone transforming, but with a gentle and soothing presence, calming them, telling them that it's okay, that yes it's intense at first but that they're finally free
Bonus points if it's a loved one guiding. Imagine opening brand new eyes, seeing the world through a new and changed light, and seeing your mate's face, and realizing that you're seeing the world like they do, smelling the scents on their fur and scales, seeing them in the way that they've always seen you~