Putting myself in this scenario (because those are the most fun things to imagine... and even possible... i'm even eating cake rn, oops), let's say as a big soft fatty myself, I would certainly be a pom-pom wielding cheerleader for helping somebody totally blob out. Like, don't get me wrong, I'd be indulging and allowing all my hedonistic desires to turn me into even more of a sofa crusher, but I have BIG feeder tendencies and stuffing somebody silly to the point of rendering them helpless hogs is super hot. If you hang around me, you're gonna get FAT.

For other scenarios, particularly the "feederism out of nowhere" type story where WG curiosity gets the better of a skinny girl or boy, I kind of like it when they are insanely bent on becoming fatter than anybody thought possible, much to the horror of their friends and family!