For Fellefan, obviously
You said that you like natural rat colors, so I went with blue and black. The blue is a little bit exaggerated, but if you really want a traditional blue you can just lighten and gray it a bit. It's based on the Variberk marking, although I added a back stripe and a mask, just to make it a little more fun.
You said you like pink, purple, and emerald green accessories, so I came up with the idea of a tail bow. This one is green and pink, but it could instead be green and purple, or she could just have a solid color bow and change them out. So the bow can be literally whatever color/fabric you want. It's hard to tell, but the yellow in the center of the bow is supposed to be a BELL. So when she scurries the little bell on her bow jingles and you can hear her.
IF YOU WANT A MALE CHARACTER INSTEAD, the bow can become a bowtie instead (around the neck).
You said you like easy/simple designs, and I think this is definitely easy to recreate but still cute at the same time.
And about the codes, I can let you color this to get the codes or I can post them it's up to you. I figured you might want to keep the codes to yourself though?