As some of you already guessed, Doc Carol and Mei are a couple, a really loving married gay couple. While Pepper is Doc’s son, Bella is Mei’s.
 
Mei is waaaaay younger than Carol and they met at the hospital where Carol used to work on Cloudsdale. That day Mie just found out that she was pregnant. Expecting and hoping to find some love from her parents and family and to welcome baby that will come, she only found disgust and rejection from those she loved.
 
Pepper Mint’s father is a really charismatic and handsome stallion Carol met in a pub. After some dates she discovered her condition. As soon as the stalion knew about it, he disappeared to never ever be seen again. Carol had the option to interrup her pregnancy, she thougth that maybe that was the only opportunity to have a child. She has date a few other ponies, but it never worked, so she decided to look it by it’s bright side and had the baby. Pepper has never meet his father. It kinda bothered him, why the other colts and fillies had two parents and he only one? This behaviour stopped when Mei and the new born Bella joined his tiny family. Pepper LOVES this three women and they are probably the only women he cares about right now. He was around 3-4 years when Bella was born.
 
Red Velvet’s father is a really charismatic and handsome stallion Mei met at a party. After a couple of drinks more than her tiny body and young age could handle, she found herself alone and with some weird memories on her mind. Some weeks later she discovered her condition. Mei haven’t meet that stalion ever since that day, so Bella haven’t met her father. She never cared, Mei and Carol are the only parents she needs.
 
Once Mei recieved the rejection of her whole family and found herself alone, with no job, no studies, no money, nopony caring about her when she always had everything she wanted and a baby coming, her whole world ended. If it was not finished, she’ll finish it herself. Thankfully Carol was on the watch, well she was on a smoke break actually, and stopped her from ended it all.
 
Carol adopted Mei on her home at least until the baby’s birth, just so Mei would find some time to get a job and being abble to take care of her baby and herself all by her own.
 
During the time they lived together, Mei developed a HUGE crush on the Doctor, her kidness and pure heart were some of the guilty. Doc was a bit not interested on the cotton candy child, I mean she was way too young! Mei’s mother condition made her look really mature, she was patiente, she was a really good mother, she was nice and she really loved Pepper, so she decided to give it a try. A couple of decades later, they are still married and they still love each other a lot.
 
When Bella manifestated her magical habilities, and since she wasn’t abble to actually live on Cloudsdale since she was an unicorn, the whole family moved to Canterlot, where they all still live. Pepper still lives with her mothers, while Bella is renting her own appartament.
 
By the time Bella was born, Mei was around 18-19 years old, while Doc Carol was on her early 30’s.
 
Doc Carol calls Mei “Cotton Candy”, while Mei calls her “Sweet Caroline”. That kinda turns the Doctor on.