I have been exploring it a little more, but I’m still learning about some of the popular dynamics involved. I’m also more into the cute and fluffy stuff rather than the likely more interesting cruel/sadistic types of scenarios. As a result of this, most the ideas in my head have to do with specific characters and ships. I’ll try and keep the details to the minimum on the characters writing, so it can be looked at by someone who possibly hasn’t engaged with the stuff I’m talking about.

I’ve talked a lot about stuffing and Uma Musume before, since they literally have scenes in all the media that is basically fetish bait. But, to move to feederism, I’m thinking about these athletes getting a little bigger post-retirement… and recently, my Belno/Oguri brainrot is creeping up again (me and my friends are planning on catching up with Cinderella gray). All you need to know is that Oguri (an aloof Kuudere-esque character from the countryside) participates in races and has a big appetite, and Belno doesn’t race and instead supports Oguri and acts as a pseudo-trainer beside her real one.
I made a post about them with the idea that Belno has a belly stuffing kink that Oguri unintentionally indulges, due to being oblivious of it. What I’m currently imaging is something similar, replaced with weight gain that leads to feederism. I’m thinking about Oguri getting real comfortable post-retirement, and having Belno as a bystander that’s feeling guilty about how much she enjoys Oguri getting pudgier every time they make time to reunite…
I really like the idea of this eventually turning into something where Oguri finds out about the attraction (whether or not it’s at Belno’s admission or simply because Oguri can’t be oblivious forever is something I debate…) and decides to indulge her more, even though she doesn’t have the kink. The idea being that she, 1. Enjoys eating a lot, and this gives her an excuse to pig out as often as she can, and, 2. Makes Belno, who she cares about, very happy… the scenario is basically just an even more complicated version of the stuffing post I made a while back.
I also think about Special Week x Silence Suzuka but… honestly, considering their dynamic, there’s not much to say besides Feedee Special week/Feeder Silence Suzuka. That’s really it. Fat Special Week is hot and so is doting Feeder Suzuka.

Also thought about Seika Ijichi x Kikuri Hiroi (which is honestly a ship I don’t usually care too much for). All you need to know for this is that Seika is a tsundere-ish big sis/onee sama type character that manages a music venue, and Kikuri is a drunkard (played for laughs) and bassist who’ve known each other for a while.
The idea is fairly simple, and is that Seika notices that Kikuri hanging around with her at the venue where food and drink is served + her already egregious drinking habits have caused her to ballon in weight fairly quickly. Seika becomes a sort of feeder through enabling the behavior, and has to hide her flustered state behind a practiced annoyed expression.

Not really a scenario per se, but I like ex-jock type things a lot. Especially for males. Fat + strong arms and a defined chest is super hot on a guy… soft, but strong…

Vore bonus:
Perhaps a devious observer feeds a reluctant pred until the weight gain keeps them pinned and impossible to resist further… feedings.