Author's Note
JUST TO CLEAR THINGS UP:
The first chapter is on the short side, as I originally wrote it simply to accompany an existing image, without extra chapters to follow. Further chapters will have stronger writing.
Chapter 01: Unwanted

Birds Of a Feather
Sunset Shimmer stretched, exhaling in satisfaction as she felt her muscles ache and bones crack. She rolled over in her bed, rubbing a large amount of sleep from her eyelashes. She slowly sat upright and cracked her neck in an attempt to wake herself up. Sunlight streamed through the lone window to her left, and she noticed snow piling on the windowsill.
How late did I sleep? The flame-colored pony stepped out of bed, leaving it unmade as she limped out into one of the many hallways that inhabited the Castle of Friendship. That's the last time I help Spike clean the castle windows.
She settled herself into the kitchen, noticing a plate of greens and a note from Twilight. "Visiting Starlight, left you some lunch. The kids are at school, I'll be home in time to pick them up! - Twilight. (PS, Spike was here)"
Figures. Twilight's always two steps ahead of anypony. Sunset fiddled at her salad with a fork, but wasn't hungry. She leaned heavily into her hoof and stared down blankly.
"M-Mom?" A small, stuttering voice suddenly caused Sunset to snap back to reality, and she noticed the thin green filly gently push open the door. "W-When did you get up?"
Sunset smiled warmly and walked to her daughter, abandoning the untouched plate of food. "Were you alone for long?" She dodged the question.
"Uh... no, i-it's okay." Phoenix Feather said quietly. Sunset followed her into the hallway, wincing. No, it's not. Mothers are supposed to wake at a normal time of day. "Were yo-did you-did you eat?"
"Yes."
Phoenix smiled shyly, large front teeth and braces prominently glistening. However as soon as the smile appeared, it vanished. She suddenly refused to look Sunset in the eyes, and scratched her front hoof on the floor.
It frustrated Sunset. For reasons unknown, her powers of empathy didn't work on Phoenix Feather. She'd grown so tolerant on the ability to understand exactly what others were feeling over the years that she found it much harder to figure out what was going on inside her own daughter's head.
"Phoenix... Is something wrong?" Sunset prodded, concerned for her daughter. Phoenix flinched at the question.
"Um..." She scratched at her nose and bit her lower lip, which were some nervous habits Sunset was able to recognize.
Sunset scooted closer and placed a hoof on her shoulder. "Hey, hey... You know you can talk to me about anything, right?" Phoenix hesitated, but nodded. "What's going on in that big brain of yours, huh?" She pushed her daughter's glasses farther onto the bridge of her nose. Phoenix sniffled, taking several steps back, and Sunset noticed tears forming in her eyes. "...Phoenix?" Seeing her daughter like this caused a welt to begin forming in her throat.
Phoenix looked back at her mother, and asked "I-is it true? Am I unwanted?" At the question, a stream of tears fell down the sensitive filly's face.
Unwanted? Sunset was taken aback. "Sweetie, I... Where is this coming from?" Her heart quickened its pace.
"N-n-nobody, I--I s-s-saw Aunt Twilight with them in the big room, a-and I --" Phoenix jumped. "I-I-I didn't m-mean to e-eavesdrop I s-swear! I-I-I was just-"
"Phoenix, how much did they say?!" Sunset Shimmer felt as though her heart was climbing its way higher and higher up her throat. Dear Celestia, she shouldn't hear this from anyone but me.
"N-not a lot... But..." Her legs trembled. "I-Is it true?"
"No! Why in Equestria would that be true?" Sunset tried walking to comfort her daughter, but she couldn't move.
Phoenix sniffled loudly. "W-why don't I... have a dad? Why c-can't I go-- Why can't I go outside?"
Sunset's heart broke. She felt fear and guilt rise up her entire body. She turned away from Phoenix as tears welled up, ashamed. "Phoenix... I... Before I continue... I don't want this to change our relationship." She took a few steps to steady herself. She was finding it harder and harder to breathe, and she was losing feeling in her limbs.
"...Mom?"
She felt her head slam on the hardwood floor again. The sweaty, demonic hand holding her mouth closed. The marks scored onto her skin every time. The heavy weight on her shoulders as she bore more pain than she ever thought she'd need to in order to protect her friends. In order to protect the one she loved.
"Mom!"
She was back in that house. Back to those sleepless nights. Back to the place she no longer called home.
"Mommy!"
Sunset jerked, blinking rapidly to clear the images from her mind but was met with darkness. She gasped when she felt ice-cold water touch her lips, and within a few moments her vision cleared. Phoenix Feather was standing by, holding a cup of water in the air with magic. She stayed silent but concerned as Sunset's breathing fell into a normal rhythm and she slid against the wall into a sitting position. She looked at her daughter wide-eyed. What do I even say to her?
Phoenix followed her and pressed the water against her lips until she obliged and drank a few sips. She pushed it away, embarrassed. "Sorry." Sorry? That's all you've got, Sunset? She cleared her throat and motioned to the ground next to her, where Phoenix took a seat.
"Phoenix-" she cleared her throat once more. "Phoenix Feather. I love you, you know that, right?" Phoenix looked away and nodded slightly. "Good. How much do you know about the other world? Refresh my memory."
Phoenix scrunched her face in concentration. "Um... You walk on two legs, have these things called fingers, and you have a different counterpart for everyone in Equestria, right?" Sunset nodded.
"You know how I moved to Equestria before you were born, right? Well, your..." Sunset clenched her jaw. "Your father and I went to school together. But that was many years before you were born."
Phoenix couldn't help but take an interest despite the current tension that filled the air. "He did? Really?"
"Yeah. We... met when he was a Freshman." When she noticed Phoenix's confused expression, she clarified "he was a little younger than me." Sunset swallowed as to stop herself from choking. "We weren't even friends." How much do I tell her? She's so young.
"Phoenix. Your father... Was a good man, but sometimes, good people do bad things."
It's now or never.
"I was ...raped by your father." But he wasn't really him at the time. Sunset looked away. No need to scare her with stories of the Devil. That will be an addition for another time.
Tears welled back up in Phoenix Feather's eyes. "..."
"Remember, I don't want anything to change. You're the one good thing that just happened to come out of a horrible situation. And I don't regret it for anything." Sunset smiled brushing her daughter's bangs from her face. "Okay?"
Phoenix enveloped Sunset in a hug, clinging around her neck. Sunset returned it, holding her daughter as close to her as possible.
"I love you too, mom..."