Flurry Heart found her mother napping under a blanket on the southern veranda, near the middle section of the castle's primary tower rise. "Always this same couch, on the same floor, on the same balcony. Why do you like this one so much? They're all pretty much the same," she said to herself.
"Because, my dear daughter," Cadance answered, not quite as asleep as her daughter suspected, "We're just high up enough to look over the whole city, but not so high that everypony looks like ants. Plus, I like to keep an eye on the rest of Equestria, too. Can't do that looking away from it."
"You can't see beyond the snow fields from this elevation, Mom," Flurry replied with barely a trace of her more youthful eye rolling.
"I think you've been spending too much time with your aunt." Cadance opened her eyes to scowl at her daughter. "You're letting something as silly as line-of-sight get in the way of a perfectly good poetic moment."
"Yeah, it was an okay line, I guess." Flurry Heart nosed her way under the blanket next to her mother and nuzzled her. "I was looking at some old photo albums when I was in Ponyville with Aunt Twilight, and I realized something about you."
Cadance tossed the blanket up with her wings, grabbed it with her magic, and draped it over Flurry's head like an oversized bonnet. "Is it that I was a total babe, and that you're lucky to take after me so much?"
"No, Mom." Flurry Heart rolled her eyes and sighed. "I already knew that. You remind me on my birthday, on Dad's birthday, on your birthday, every holiday, and whenever you think a colt at school looks at me for more than two seconds. I won't ever forget, believe me."
"Good," Cadance said, smiling. "But I'll remind you tomorrow just to be safe. Now, tell me what you learned with your aunt?"
Flurry's eyes narrowed as she looked at her mother, sucking all the levity out of the lazy afternoon. "You're getting old," she said. "It's hard to notice changes when you see somepony everyday, but looking back at those old pictures it's obvious. Your coat's not as bright, your back isn't as straight, and if I look real close I can see a few grey hairs under the pink."
"Mothers age, sweet heart. It's not a ground breaking observation, I hate to tell you. Maybe Twilight is losing her touch as a tutor." Cadance smiled down at her daughter, but she'd lost some of her earlier mirth.
"But you... shouldn't be, right? I mean, that's not what we do. Right? I'm still growing, so that makes sense, but Aunt Celestia and Aunt Luna have looked the same basically forever, and Aunt Twilight looks about the same now as she does in her coronation photos."
"She's a little taller and her horn is longer, if you look very carefully," Cadance whispered to her daughter in a half hearted effort to steer the conversation anywhere else.
"Okay fine, but why are you the only one going grey and napping more?" Flurry asked, clearly not taking her mother's bait.
Cadance sighed, and draped a wing over her daughter. "Mothers age, dear. As I said."
Flurry pushed away from her mother's embrace. "You mean I'm the reason you're aging?"
"I am the reason, Flurry Heart, nopony else." Cadance gestured for Flurry to sit beside her again. "A while after you were born, your aunts asked if there was anything unusual about my pregnancy. Since there had never been a natural born Alicorn in Equestria, you were kind of a big deal. I said everything was textbook from conception to birth. That was a tiny lie of omission. Ever since we got together, your father and I were very—"
"—Mom—"
"—affectionate, sweetheart. But, no matter what, I didn't get pregnant. Which was great, for a while. But then we got married. I thought more and more about being a mother. One night, after... well, after, I thought about what would happen if I could never have a baby. Never make Shining Armor a father. I wanted you, Flurry Heart, more than anything else in the world."
"Mom, I—
"It was like a switch flipped inside of me, and I just knew. The cost of life is life, dear, and I paid it happily. A few weeks after that night, I started throwing up every morning and suddenly couldn't eat pickles unless they were fried and dipped in chocolate."
"So, you gave up—"
"Nothing, compared to what I got. Uncountable amounts of dirty diapers, I don't know how many thousands of cans of peas, a hundred and one tired tantrums, countless sleepless nights..." Cadance pulled the blanket off Flurry's head and wrapped it around them both. "One perfect daughter."
Flurry Heart fought back tears as she snuggled close to her mother. "Why lie? Maybe my aunts would like to be moms someday, too."
"They're smart mares, Flurry. They'll figure it out, if and when the time comes. Just like I did, and just like you would have if you had spent the afternoon chasing boys like a normal teenager and not hanging out getting existential with your mother."
Cadance and Flurry Heart sat together quietly, watching the afternoon sun trace it's shortening path across the clear Autumn sky. The air chilled as the sun dragged closer to the western horizon, but neither mother nor daughter felt like escaping back into the castle yet.
"Am I the same as my aunts? Or am I like you, because I came from you?" Flurry finally asked as the sun touched the peaks of the mountains.
Cadance hummed quietly to herself as she stroked her daughters mane under their blanket. "Only time will tell, Flurry. But, I'll tell you the same thing I told Twilight when we talked years and years ago: it doesn't matter. Not really. The joy in life comes from how we live, not how long."
"We should probably get inside before it gets any colder." Flurry hugged her mom tight and helped her up off the couch, not that she really needed it. "You know, Mom, you're pretty smart for an old mare."
"Comes with the job, sweetheart," Cadance replied, only momentarily annoyed at being called old. "Afterall," Cadance opened the door back into the castle and nudged Flurry though.
"Motherhood is magic."