Hey Teetree, hello and welcome;
Looking at your pictures, I would say those are aphids and it looks like your growing medium is unfinished compost, a good idea if you are sheet mulching but not so much in a pot ( my opinion anyway ). The composting process can be a literal zoo for micro organisms, some good things some not so much. Soapy or alcohol water misted on the plants, diatomaceous earth application, or catching ladybugs will/should help. But I seriously think your pot and soil may be the problem. If you live anywhere near a nursery, see if you can get your hands on a discarded nursery pot, 5 gallon or bigger, the color would induce heat and block sunlight, which would greatly reduce the Bio-activity below the soil surface.
Also, I would humbly suggest you plant each pepper in their own pot. Just to isolate and contain any problem and limit it to just the one plant. Good luck!
