Hi! There is diapers, which focuses more on the DL aspect. That does include seeing used diapers at times. (Visually discoloring and shape will be changed/or seen with this on them.)
Below are a few that stick out that might be more fetish hit or miss for some, but these below ones are more linked to when you get into route episodes with a girl. (These should be hinted at before getting into their route.)
-fart/aroma fetish
-bdsm/femdom
-watersports
-humiliation
-petplay
-crossdressing