"HOLY CRAP I'M IMMORTAL!" Twilight shrieked suddenly.
Starlight Glimmer gave her an odd look. "...Yes. Yes you are. Are you... just now realizing this?"
"I--N-no!" Twilight protested, flushing oddly as she refused to meet her student's eyes. "I just... wanted to shout that! Yeah!"
"Oh...kay then." Starlight cleared her throat, once more looking down at the parchment in front of her. "So, this map of the palace--"
"WHO CARES ABOUT THE MAP?!" Twilight roared. "IT'S WORTHLESS!" She flew up to the bookshelves and started ripping whole tomes to the ground. "EVERYTHING IS WORTHLESS!"
Starlight backed up. "Twilight? Are you feeling okay?"
"...oh sweet Celestia. I--I'm so soooooooorrrrrrryyyyyyy!" The alicorn swooped down, blubbering inelegantly as she wrapped her hooves around the unicorn's neck. "I'm such a meeeeeeeanieeeeeeee...."
"...Okay, I'm going to be totally honest here: This entire situation is scaring me."
"You know what always calms me down when I get scared?" Twilight perked up, giving her student a brighthappy grin. "Ice cream! Tubs and tubs and tubs and tubs and tubs of ice cream! It tastes great!"
"You know what? This is a friendship emergency." Starlight pushed her off, turning toward the door. "I'm going to go get your friends, and they're going to deal with this, okay?"
Twilight's dead stare was barely visible from behind her bangs. "I have no friends," she droned. "All I have is the temporary illusion of companionship provided by a few short-lived mobile sacks of flesh, only different in the fact they choose to associate with me."
"...wow, that's depressing."
"Oh, sooooorry! Don't want you hurt your precious little feelings!"
Starlight leaned away from her livid face. "Twilight, you do realize you're having moodswings so rapid that basically every time I open my mouth you go from--"
"OHMYGOSH!" Twilight jumped forward with a huge grin. "I CAN SEE ME IN YOUR EYE! HELLOOOOOOO MEEEEEEEEEE!" She giggled. "I am a pretty pony!"
Starlight took a breath. She lowly let it out. She contemplated, not for the first time, the exact series of events that had brought her to this place, at this time. This, obviously was just another part of her atonement. One that didn't make any sense, but which was happening.
"Twilight, I--"
"I will eat your heart when you die."
"...WHAT?!"
"That way, you'll be with me forever! And ever and ever and ever and ever and ever--"
"Twilight, that's not how necromancy even works!" Starlight pointed out in exasperation.
Twilight held up a hoof for a second. "You have a..." She stared at her hoof, twisting it left and right. "Wait... where are my fingers?"
"Fingers--Twilight, you're a pony. Who's apparently been drugged."
"YOU DRUGGED ME?!" Twilight shrieked, stumbling back in horror. "STARLIGHT HOW COULD YOU?!"
"I didn't do it!" Starlight protested. "You're the one that's--why am I even arguing this, I need to get you help."
"Don't go!" begged the alicorn, latching onto her rear leg. "Please! I don't want to be alone!"
"Well I can't exactly take you out while you're like this!" Starlight grunted, trying to tug her leg free of the surprisingly tight grip.
A salacious smirk formed on Twilight's face. "Who says we have to go out at all?" she purred, clambering slowly up Starlight's flank.
"Wh--I--" Starlight flushed. "Twilight, you're not thinking straight! I'm your student, not your marefriend!"
"You---you don't want to be friends?" Twilight whispered, tears threatening.
"Of course I want to be friends!" Starlight cried in exasperation. "And since I want to be friends, I'm legitimately worried about you! That's why I'm trying to get you help!"
"I don't need your help!" the alicorn insisted, shoving her across the room. "I don't need anyone's help! I'm perfectly fine on my own!"
"YOU'RE NOT FINE!" Starlight exploded. "You're going from crazy happy to crazy angry to crazy sad at the drop of a hat and you're getting ideas like eating hearts and thinking ponies are just walking sacks of flesh and also trying to feel me up which is not okay we need to at least have gone on like five dates or something even if you are pretty but that's entirely besides the point which is you are not acting normal in any way whatsoever and you need help and I don't know how to get it but I am going to get it because that's what ponies do when ponies freak out and you are just going to SIT HERE until I get back with somebody who knows what the HAY is going on!"
She glared at the alicorn, huffing and panting in frustration.
After a moment, Twilight raised a hoof awkwardly. "Um. I can explain this."
"REALLY."
"Yeah, it's... Longevity Unilateral Mental Projection Syndrome. Celestia told me about it when I became an alicorn." She coughed into her hoof. "Basically, there's a part of my brain that factors in all the implications of immortality, and keeps them from affecting me too much. It just, you know, occasionally needs to be purged, which... releases a lot of hormones, and, yeah, makes me act crazy..."
Starlight blinked.
"Wait... what?"
"Yeah, that was my reaction too. I didn't actually believe her until I saw what Celestia went through, and... she's been purging once every two years for centuries now. Even then, she goes bonkers." Twilight rubbed the back of her head. "Thing is, this was actually my first case of the LUMPS, so... I didn't know what to look for."
"So what you mean to tell me," Starlight said slowly, "is that alicorns have a part of their brain that drives them temporarily crazy at regular intervals."
Twilight nodded. "We're pretty sure Nightmare Moon was caused by a hormonal imbalance in the Imortallis Gland."
"I... the leaders of ponykind... regularly go insane."
"Yes."
Starlight stared at Twilight.
"...that's it. I'm done. I'm out." She turned around, ready to leave.
"Hey Starlight?"
The unicorn sighed. "Yes?"
"...thank you for staying with me. And trying to help. And..." Twilight flushed. "Could you... not tell anypony about this?"
After a moment, Starlight Glimmer shrugged. "Well, if you don't try to eat my heart out, I'll consider it."
