Make him FAT

While Rick tends to gain weight more easily because he has a slower metabolism and has a tendency to like junk food he's also the one that's not as tapped in into feederism. He likes being pampered by Jiang and Jiang likes spoiling him with his cooking, so at most he just gains healthy relationship weight. If Rick ever does tend to overdo it he gets more nauseous than horny but he can warm up to the idea of gaining 🙂‍↕️

Jiang on the other hand is a little different, he's spent most of his life being restricted. Every aspect of his life was laid out and planned for him including his diet and that bled over to how he conducts himself present-day. (Funny because he actually envied Rick for being able to eat whatever he wants whenever LOL.)