Here's an idea for a fanfic (An alternate take on Marks for Effort).

After being wrongly accused by Twilight on making Cozy Glow fail her test, the Cutie Mark Crusaders get into a heated argument with the Princess of Friendship and their sisters. It ended with the three filles calling Twilight a fraud and the worst princess ever before running off in tears, leaving the four mares in shock and heartbreak.

The CMC run away from Ponyville before they end up getting lost. Feeling betrayed and upset, the three of them wondered what to next. They then stumble across a cave. At first they are hesitate to go in, but they soon have no choice as a thunderstorm then hits.

Once inside, Apple Bloom, Sweetie Belle and Scootaloo look around. Then, they hear a sound. Curious, the three filles go deeper into the cave.

After going on for what felt like hours, they soon find out what was making the sound, or rather who.

Turning a corner, the CMC gasped in shock for standing in front of them is none other than the ex-queen of the changelings herself, Queen Chrysalis!

At first, the girls get very scared until they notice something. Chrysalis looked so....different. She didn't seen like the evil queen they, their sisters and friends saw at Shining Armor and Cadance's wedding, instead she looked tired, sad and quite lonely.

Chrysalis was surprised to see the fillies. After seeing how scared they looked, she spoke softly to them, reassuring them that she has no plans on harming them.

Confused and curious, they asked what was she doing in the cave all alone.

Chrysalis sighed sadly before explaining. After being defeated by Starlight and Thorax, she ran off, plotting her revenge. However, while going undercover she noticed how happy many ponies were together. She then realised that there's a better way to get love than stealing it. Now with change of heart, Chrysalis had remained in her cave, wondering how to make amends with all those that she had angered. She then pointed over to another part of the cave where her stuff of survival is (A queen-sized bed, a flashlight, food, water and many other things).

The changeling then asked the CMC what they were on their own.

Apple Bloom, Sweetie Belle and Scootaloo started leaking tears as they explained to Chrysalis about what happened to them.

Chrysalis felt for the little ones and asked them if they would like stayed with her for a while. Despite being a little suspicious, the fillies decided to stay, not just because they were still feeling upset about the bad argument they got into with their big sisters and Twilight, but also because they had no choice since the fierce storm was still raging outside.

As the weeks went by, the CMC started to warm up to Chrysalis and began to see her as a mother-figure to them, likewise Chrysalis began to look upon them as her own beloved daughters.

One night, after sharing stories and playing games, Chrysalis send the girls to bed. As they climbed in, the Crusaders then admitted to Chrysalis that she makes a great mother-figure to them and they even added by saying that they wished she was their real mother (With Apple Bloom calling her "Mama", Sweetie Belle calling her "Mommy" and Scootaloo calling her "Mom"). Chrysalis was rather surprised, but also touched by this. She smiled a big motherly smile as she tucked the filles in. The changeling then started to sing a beautiful lullaby to help get them to sleep. Soon, one by one, the CMC fell asleep, wearing big happy smiles on their faces. Chrysalis smiled at how cute they looked while sleeping. She gave each of them a kiss on the forehead before climbing into bed with them. For the first time since their bad experiences, the four of them felt truly happy.

Of course, as much as she loved hanging out with them, Chrysalis would soon have to return Apple Bloom, Sweetie Belle and Scootaloo to their families, especially after hearing that Ponyville was hit hard by the storm weeks ago. While thankfully everypony (Including Applejack, Rarity, Spike Rainbow Dash, Twilight Sparkle, Fluttershy and Pinkie Pie) had survived, unfortunately the School of Friendship wasn't so lucky, and neither was Cozy Glow...