These days, Kailyn Lowry and Leah Messer are the best of friends, and Chelsea Houska is generally considered to the kindest and most relatable of all the Teen Moms.
But according to Kail, that wasn't always the case.
On a recent episode of her "Coffee Convos" podcast, Kail harkened back to the time when she was first cast on 16 and Pregnant, the predecessor to Teen Mom and Teen Mom 2.
And it seems that her co-stars were less than welcoming in those days.
"There was a time when we first started Teen Mom. I came in late," Lowry explained.
"I was not supposed to be on Sixteen and Pregnant Season 2. I was supposed to be on Sixteen and Pregnant Season 3," she continued.
"So I was a last-minute exchange to move to Sixteen and Pregnant Season 2."
Kail went on to reveal that in her earliest days on the show she was very much a fish out of water.
"Everyone had already known each other. Chelsea and Leah were like besties on the show," she said.
"I felt like I was always the second choice to them. I was always second best. I was always an afterthought."
Kail says that with other members of the Teen Mom family, she felt like a "B-List friend," as she would only receive invitations if "Chelsea and Leah were busy,"
"I may be a B-List friend for somebody else but I don't give a sh-t," she added.
Obviously, this is all very surprising.
Chelsea is the most popular Teen Mom by almost any metric, and one of the reasons she's so beloved is the universal, unconditional kindness she's displayed over the years.
Leah and Kailyn go on vacations together and regularly refer to one another as best friends.
Their relationship is so close that for a long time, fans were convinced that Lowry and Messer were dating.
But it's important to remember that these woman were mere teens when this show started (hence the title), and the sad fact is, teenagers often engage in unkind or insensitive behavior.
Have Leah or Chelsea reached out and apologized to Kail after learning how she felt in those early days?
We have no way of knowing, but in a way, it doesn't matter.
After all, the three of them have been close friends for nearly half their lives at this point, and any friendship that goes on for that long is bound to have a few ups and downs.
Speaking of ups and downs, on the same episode, Kail revealed that she's on relatively good terms with Javi Marroquin -- but she's completely cut ties with Chris Lopez.
"Javi and I still, I would say, he has harder periods than I do right now. Where I've like completely mellowed out," she told her co-host, Lindsie Chrisley.
"I just don't react the same anymore and then Chris and I just don't communicate at all," she continued.
"I don't have a relationship with Chris at all, we don't communicate whatsoever."
So if there's anything that the younger audience can learn from the latest episode of Kail's podcast, perhaps it's this:
Relationships are complex and difficult when you're young, and ... well, unfortunately, they continue to be complex and difficult when you get older.