It was raining one night with the only light coming from the moon in the sky and occasional lamp in the street. It was a simple Canterlot night. Or so they thought.
The guards walked the hallways, keeping alert for anything, such as Twilight trying to steal an ancient scroll or spell tome. Again.
But that night, for some guards, was different. Moving shadows, tapestries swaying with no wind and that eerie sense that tells you you're being watched were familiar companions for the guards on patrol. Though, at the time, it was shrugged off as the night playing tricks on them.
The princesses were doing what they normally did at that hour, Celestia was in bed and Luna was reading all the Daring Do books, which she got into after getting back from the moon hardly a year before then. But in the darkness crept two figures who were definitely not royal guards. And due to the rain and shadows nopony saw or heard a thing. Not a thing that is, until an act that hasn't even been spoken of for decades happened that very night.
Luna was out on the balcony reading her book for she took a liking to the sound of rain, she found it calming. But right as she was almost done with the last chapter she felt something stab into her left wing, making her scream in pain. But the attacker was immediately sent flying into the bedroom by her magic. Luna got up, pulled the weapon, it was a knife, out of her wing, luckily it was a small knife and only rendered that wing useless until she could get medical attention, and walked into the room, knife in her magic.
The attacker fell from the ceiling onto her back but had to jump off to avoid their own knife only to be thrown into the door by Luna's magic, shattering it and, most likely, alerting the guards. But the attacker only got up and held another, longer knife in their mouth, Luna noted that they wore a black garb and some kind of mask covering their face from view. They lunged forward but Luna flapped her working wing and slid to the side and bucked them right out onto the balcony.
Luna sent the knife flying at them, so when the attacker got up and turned they turned their head but got cut, cutting away some of the mask and causing a lock of yellow hair to fall to the ground. But as they were falling, once more, onto their back Luna galloped and was on top of them to cast a spell but got bucked. One hoof hit her head while the other connected with her forehead, causing extreme pain to her horn and dissipating the spell, as well as sending the princess reeling back and falling on her side.
The attacker picked up their big knife and would have ended the princess of the night then and there if the guards hadn't arrived. The attacker gave a grunt of anger, threw the knife to the ground and jumped off the balcony into the night. Luna, still stunned and dizzy from the hits to her horn and head, tried to tell the guards she was fine and to check the castle and give chase but they either wouldn't obey until she was safe or her words came out slurred due to her head wound.
Two guards approached the balcony and looked over it's edge but saw no sign of the attacker. They would have investigated then if it weren't for another crash that sounded at the other end of the castle, from Celestia's room.
For just moments before Celestia had a similar encounter that went as follows.
Celestia was having a wonderful dream about having a picnic with Twilight, Twilight's friends and her own sister Luna, who had yet to go on one, when she awoke to her silent alarm spell, she cast that spell every night before bed after Discord did something by sneaking into her bed chambers one night long ago, the spell's purpose is to awaken the caster when an intruder breaks in quietly.
Celestia opened her eyes but remained still. She then turned over causally, like ponies would in their sleep, to see a pony covered in black holding something in their mouth. Instantly Celestia went into thinking mode much like her own student would. Who are they? What are they holding? Why are they here? Sadly while in thinking mode she didn't see the intruder come up to the side of the bed until it was too late.
The intruder wrapped what was in their mouth around each of their fore-hooves. It was then Celestia broke out of thinking and tried to cast a spell. But the intruder thought quick and flicked her horn stopping the spell. They then quickly wrapped the line of either rope or wire around Celestia's throat and started to tighten it. Celestia felt the cold of metal, it was a wire.
Celestia tried to push the intruder off of her with her hooves and magic, but when she tried they would jerk wire causing more pain. Then she got an idea, she unexpectedly flared her wings. The intruder fell off balance and fell to the ground though Celestia's head went with them. The intruder was dazed a bit leaving Celestia free to use her magic to break the wire.
Gasping for breath, Celestia rose her head and jumped to the other side of the bed and waited for the intruder. But they never came. Celestia, both weary and curious, walked around the bed to find the intruder gone. Surprised, Celestia looked around but couldn't find them. Thinking that the intruder escaped she made her way to the door, but before she made it something fell onto her back and felt two hooves hit her wing joints, she would have screamed in pain but her throat was still recovering so all it was was a raspy, almost inaudible exclamation.
Celestia threw her head back, connecting with the intruder's and sending them crashing onto a wooden table, breaking it. Celestia turned around to see the intruder getting up, a few pieces of wood sticking to them. But as they lifted their head the mask they wore caught on a big and sharp piece and tore some of it off. When the intruder looked at Celestia she saw two purple eyes filled with hatred and burning desire for something that she couldn't identify. The intruder grabbed a big piece of the wood and swung it at Celestia hitting her head and dazing her before hitting her repeatedly. Celestia saw through blurry eyes as the intruder ran somewhere when they heard the door open.
Celestia turned her head to see two blurry visions of her guards run towards her asking muffled questions about her safety. Before she passed out from the sleeping spell one of the guards was casting on her she made a mental note to send a letter to Twilight and her friends. For they aided Celestia and Equestria time and time again they would surely help this time as well. And they are not as obvious as her guards. Celestia knew that under the Elements of Harmony that intruder would rue the day they tried to eliminate the Princesses.