How do I create an custom NPC and tie it to my mod?

[Grundy122]

I wanted something like Father Winter, an NPC that never changes physically.

 

It's for a cuck / NTR mod idea I was thinking about doing down the line. One of the things I wanted to make work is that to advance in a certain custom career, the husband needs to fulfill the requirement of "inviting boss to dinner" each career stage.

 

And I sort of wanted the boss to always be the same, so I could costumize him with traits like giving an broadcast buff that makes married NPCs flirty, or something. I'm still doing the GDD for this thing.