Princess Luna ran off when Celestia and Discord began to get into a heated argument that lasted for only 10 minutes, but it was it was bad enough that it scared Luna off to her bedroom as she tried to blot out all the yelling the best she could. Shortly after the her argument with Discord ended, she went to check on Luna to see if she was ok.
 
“Luna, can I come in?” asked Celestia on the other side of the door.
 
“S-Sure.” Luna replied meekly, as she was still hiding under her covers, still worried something could happen to her.
 
Celestia walked into the bedroom and closed the door behind her using her magic. She walked over to Luna’s bed and sat down next to the scared moon princess.
 
“Are you alright, Luna? You got so scared when we started arguing and ran off that I want to make sure that you’re alright.” Celestia said calmly.
 
Luna looked up from under the covers, feeling still abit scared but calmer by hearing the tone of her sister’s comforting voice. “I-I’m still abit shaken up, but I think I’m a tad better now.”
 
Celestia could still see Luna’s eyes were still filled with tears, the sight breaking her heart as she never wanted to see her sister cry for any reason. The sight caused Celestia’s own eyes to begin to water as well.
 
“I’m sorry my argument with Discord sacred you, Luna.” Celestia said as she placed one of her wings protectively over Luna. Using her magic, she made a piece of dark colored caked appear on a sliver plate with a fork sticking upright out of it. “Please accept this moon cake as my offical apology. I didn’t know the argument was going to become that bad.”
 
Luna looked at her sister with a slight smile and tears still in her eyes. “It’s alright, Tia. I understand why you had to argue with him. He insulted you and you didn’t deserve that.”
 
“When he called me a dictator towards my subjects, it set me off. You didn’t deserve to even hear that argument.” Celestia said as she tried to keep the anger down in her voice.
 
Luna nuzzled her head against Celestia’s neck. “You’re not a dictator, Tia. I know this because you are the kindest pony I know. You’re the best big sister and I love you.”
 
Celestia couldn’t help but let the tears fall down her cheeks at her sister’s touching comment. She rested her head upon Luna’s. “Thank you, Luna. Perhaps you should enjoy your apology moon cake.”
 
Luna smiled. “Let’s share it together, Tia. We both need the healing powers of the moon cake.”