With the world beneath her heel and no one left resisting her, Salem had nothing to do but celebrate her victory with her right-hand woman Cinder Fall.
"I've had every baker on Remnant ordered to make us as much cake as they can, and every cattle farmer to provide us with as much fresh milk as they can. I feel that this will be a celebration to remember," Salem said smugly as she slouched in her black metal throne. Cinder, in her slightly smaller throne next to Salem's, raised an eyebrow as she heard Salem's announcement.
"Cake, Salem?"
"Of course, girl. I am only human after all, or at least human enough to appreciate cake, and what cause for celebration warrants cake more than the total subjugation of Remnant?" Salem stated. Cinder nodded in agreement and her arguments were gone.
Some time later, a table with a frankly ludicrous amount of cake of all flavours, shapes and sizes and milk was carried in. Cinder's eyes widened and Salem licked her lips as she leaned in.
"Well, go ahead," Salem told Cinder as she grabbed a knife and began cutting slices of cake for herself. Cinder sat and stared at the vast vista of practically endless cake.
"This seems… excessive," Cinder said quietly. Salem swallowed her first bite quickly and turned to face Cinder.
"We have all the time in the world to eat this, and I could hardly expect us to finish this all today," Salem explained, before a sneaky smile slipped onto her deathly white face. "Besides, if you're not interested, I am more than happy to have this all to myself."
"It's fine, I'll just have a small portion," Cinder said, before cutting herself a little slice.
Over the next few days, it was clear that Salem was the one enjoying this the most. She was cutting herself some increasingly large slices and stuffing her face with the vast array of cakes on offer and washing it down with luxuriously creamy milk until she was as stuffed as can be. For the first little while, Salem usually slowly headed back to her private room to rest and recover before going back for more, but after a while she thought that was just a waste of time, so she just napped in her throne before waking up and getting straight back into the cakes. Before too long, Salem decided to save even more time by skipping cutting the cake and just grabbing the trays, lifting the cakes up to her face and biting into them, chewing her way through them before tossing the tray aside and going for more, more than happy to let her gluttonous desires take over. Cinder, on the other hand, took longer to start eating with the same reckless abandon as her mistress. Her portions were very sensibly sized, and she even included regular, healthy meals and exercise in her time, as opposed to Salem, who subsisted entirely on cake and milk, and eventually barely even bothered with getting out of her chair, let alone exercising.
It wasn't long before the effects of their new diets were visible. Cinder looked much the same as usual, maybe slightly less lithe and slim, nowhere near big enough for any rational person to complain. Salem, on the other hand, was very obviously getting fat. Her jet-black robe grew snug around her jiggly double belly, the top roll generally firmer that the bottom as it covered Salem's almost perpetually full belly. Her rear had grown plumper and wider, aided by the fact that Salem had barely moved for quite some time from a throne that was starting to get to be a bit of a tighter fit. Her chest plumped up, straining the top of her gown and making a very visible deep cleavage at the diamond shaped gap by her chest.
Seeing Salem's example, Cinder found herself going for larger portions, exercising less and eventually slipping into Salem's sedentary and gluttonous lifestyle. Salem have eventually gotten even lazier and even more gluttonous, creating Grimm with the specific purpose of bringing cake and milk from the table directly to her mouth so that she didn't even have to move for that. Salem offered to make some for Cinder, and to Cinder's credit, she did resist for a while, but eventually her desire to follow Salem's example, plus her desire for more to lord herself over, led to her getting her own set of feeding Grimm. When Salem later made herself some Grimm to rub her growing belly to help settle it in the short breaks that she took between stuffing herself beyond belief, Cinder soon asked for her own and was very happy when she got them. The pair had everything they wanted and enjoyed their laziness.
With very little reason or need to move, Salem and Cinder's weights skyrocketed. Their thrones grew too small for their fat rears and had to be resized regularly. More Grimm were needed to keep up with the women's increasing appetites and increasing needs for more and more food. When the cakes eventually ran out, Salem and Cinder were massive, their outfits were in shredded tatters and their appetites were immense. Cinder was the smaller of the two, but calling her small was very incorrect. She ended up with an overfilled hourglass figure, with a rear so wide that her seat was about twice as wide as when she first got it and her massive breasts were so large that she couldn't even see past them. Her gut was no slouch, being a mammoth plump ball of fat that filled her lap when she was seated. Occasionally there would be tatters of her red dress to cover something, but for the most part, Cinder was basically nude all the time. Salem, on the other hand, was definitely naked all of the time, as she was so large that none of her clothing survived. She had grown another roll of fat on her blubbery belly, which was the main focal point for anyone looking at her due to its immense size, wide as the rest of her and large enough to spill over her thighs and also being white as snow. She was so wide that her throne had to be three times wider than it was when it was installed, and even then, her pillowy fat rear still spilled over the sides and her titanic thighs were squeezed together by the throne's sides. Her heavy, uncovered breasts were each about the size of Salem's head and always spilled out of Salem's hands when she took the time to cup them or squeeze them or play with them. Her arms were flabby all over and even her face had changed, going from the sharp, stern visage to a round, soft thing with an extra chin or two.
"Well, looks like we need another source of food," Salem said, before letting out a window rattling belch. "Any requests, Cinder?" Cinder groaned as the Grimm massaged her big and bloated belly.
"Food," Cinder said mindlessly, her eyes glazed over as she lay back and enjoyed the pleasure of the massage. With that, Salem sent out another order for any food that Remnant could provide. There was no way Remnant had enough food to satisfy their rotund rulers, but all they wanted was food, and food they would have.
[AN: This was another request by Hello-AgainDA over on DeviantArt. You might be asking "Hey Mr. DudeManGuy, if they took over the world, what happened to RWBY and JNR and everyone else?" And to that, my answer is "Don't worry about it. Seriously, just don't. I did not think this through and I am not very good at writing villains doing villain things."]