Shining Armor walked into the bathroom, levitating his little sister by the tail with a light red aura of magic. A filly Twilight was two feet off the ground, a grumpy look on her face caused by her brother's victory over her. Shining Armor, on the other hoof, was smiling with pride as he brought to you his trophy.
"Thank you, Shining!" you say happily, feeling fortunate that he was at your assistance (he volunteered to when he heard).
"No problem!" he responded, still smiling. He placed the young violet unicorn gently on the ground right-side-up, and Twilight stayed, knowing that resistance was futile with her brother. She was not amused at all, for, as Shining told you, she was in the middle of doing her "homework" with Smarty Pants.
"No baths!" said the grumpy filly with her arms crossed.
You were surprised that the filly before you had just talked, even though you knew she was smart. "Wow, she can already talk!" you comment to her older brother.
"Yeah, but only basic stuff," responded the colt, who was levitating his sister by the body this time, placing her in the bath.
"Ah," you say, moving to the tub in order to start the child prodigy's bath. You kneel next to Shining Armor, who is leaning over the rim of the tub, talking to his baby sister, attempting to comfort her with little success.
Okay, let's start this you think as you grab the bottle of shampoo Shining hands you. You thank him as you squirt a handful in your palm. You then start to lather Twilight's grape and pink mane, making sure not to get too close to her horn (Shining had said earlier that she hates having her horn touched). Because of her short hair, this only takes you half a minute. You turn to Shining and give him a nod.
Shining Armor nods back, and you see his horn glow. Suddenly, a medium-sized ball of water floats out of the water and levitates over Twilight's head. Then, Shining releases his magic, sending the ball of water falling on his sister's head. Twilight is shocked by the sudden water, so much that she begins to cry. Although this seems to uneffect Shining, who continues rinsing her mane, it shatters your heart to see the little unicorn cry. When Shining is done after four more rinses, he leans closer to his sister and begins to talk to her.
"Hey Twily," he says in a soft, soothing voice. The filly stops her crying for a second to see what her brother had to say. Shining, with his sister's attention, places his hooves over his eyes, asking "Where's brother?" When you see the filly put on a confused look, her brother removes his hooves from his eyes, yelling "Peekaboo!" The little filly giggles cutely at the little game. Shining repeats these steps three more times, gaining another giggle each time.
You smile warmly at the memories you've had playing peekaboo. When Shining is finished playing, he turns to you. "You're a great big brother, you know that, right?" you say to the colt looking up to you, smiling at the compliment.
"I get that a lot," said Shining humbly.
You nod again and return to the bath. Grabbing the shampoo bottle again, you ask Shining to lift her tail while squirting some more soap in your hand. He magically lifts his sister's behind for you while you begin to lather her tail. This process takes twice as long as her mane, considering her tail was longer and, for some reason, dirtier. You mention your findings to Shining, who kindly explains.
"She accidentally sat in some mud outside," he explains.
"Ah," you say again. "Well, I finally got it all out."
Shining nods again and conjures up another ball of water. Still holding Twilight's tail up, he begins to recreate his past method of rinsing out the shampoo. Twilight is not surprised by the rinsing this time, and instead begins to laugh. You figure that she is either ticklish, or just happy her BBBFF is near. This process of utter cuteness continued for four more ballfuls of water before her tail is completely clean.
With Twilight fully clean, you take out a few bath toys and place them in the water. Twilight lights up, handing her brother a toy boat while grabbing one for herself. The two siblings begin a little bout of roleplaying, Shining being the great big brother he was. Two minutes of Twilight half-talking, half-babbling and Shining somehow communicating with his young sister go by with you looking over them, smiling. This, you figured, was your best idea yet that day.
When the time for playing was over, you interrupt the sibling ponies and take the toys. Shining easily gives up his toys to you in a mature way which you admire. Twilight, on the other hoof, refused to let go of her red plastic boat.
"Now, Twilight," Shining says to his sister, "give the nice sitter the boat so you can get out of your bath."
Twilight lets go of the toy, which you pick up and place on the counter behind you. She starts to tear up a bit, almost diminishing your determination. She then reaches over the tub to the boat as though she could somehow get it. You look over to her toy, only to see it floating in the air! The boat then glides over to Twilight, whose horn was shining a bright purple. You're taken aback by what had happened: Twilight just used magic! You look to Shining for an answer.
"She's determined," he explains. "That's how magic works: pure unicorn determination."
"Ah," you say one last time, almost annoyed at the word. That explains Pumpkin Cake. Never in your life would you think to have learned that by giving a pony a bath! Impressed by what she did, you let Twilight keep the toy as you unplug the bath and take her out.
Shining magically levitates the blue towel next to him and brings it up to his sister. He begins to shake the towel over her head, drying her mane. Then he moves on to her body, and then her tail, and finally her hooves. With his sister fully dried, he puts the towel in the hamper and turns to his LSBFF (Little Sister Best Friend Forever).
"So," said Shining friendly. "Want me to read you 'Goodnight Luna'?"
Twilight beams at the mention of her favorite story and skips outside the bathroom eagerly. Both you and Shining laugh, following the ecstatic unicorn out the door.
You see Twilight and her brother cuddle up in her room later on, an open picture book in Shining's hooves. You smile at the sibling bonding, your heart warming at the sight.