I'm not sure if this can be called a fetish, but it's the common theme I've enjoyed across some hentai games I've tried or heard about. Examples include:
- Raising devoted, trusting, healthy, and happy slaves by acting as a paternalistic master/mistress in Free Cities.
- Rescuing homeless, back-alley criminals off the streets by providing room & board for them in Lilith's Throne.
- And, of course, anything similar in premise to Teaching Feeling or Gran Ende II.