Luna gasped as the spell finished, experiencing vertigo from the sudden return to reality.
Twilight panted. "Oof, that was a long one. You okay, Princess?"
Luna didn't respond.
"Princess?"
Suddenly, Luna stood up and bolted around the table, lunging into a hug with Cosmic.
Said stallion blinked. "Does... Does this mean you remember me?"
She looked him in the eye and grinned. "Does this answer your question?" Without any further warning, she pulled him closer and gave him a long kiss on the lips, to everyone's surprise.
When she drew back, he grinned. "I suppose it does."
Celestia made an obvious throat-clearing sound, drawing their attention away from each other. They both blushed.
"Ahem", Luna actually cleared her throat, "Twilight, Spike, the Crown thanks you for your services."
Spike tried to object, "But I didn't do—"
"Now, if you will excuse us, Cosmic and I have some 'catching up' to do." With that, she teleported the two of them out of the room.
Celestia frowned. 'The Crown'? That was Old Equestrian, and Luna had long since abandoned the use of that.
Something was going on, and Cosmic was at the center of it.
The next day, things began to change around the Castle. Luna assigned the Royal Carpenter to remodel her room so that it could fit two; meanwhile, Cosmic was given a temporary guest room. Even so, they visited each other every night, since there was still plenty catching up to do.
But not all was well; Luna began to become increasingly agitated whenever the servants messed something up. She often reverted to Old Equestrian, and once even used her Royal Canterlot voice to scold a maid that walked in on them while they were together. She also began shirking her duties somewhat, eager to get the day over with as quickly as possible so she could see him again.
Celestia watched all this play out for three nights, then decided that enough was enough.
Cosmic exited Luna's room, looking the happiest he'd ever been. Luna poked her head out and smiled, "By dusk, our chambers shall be ready for two. We bid you a good day, luv."
"Good day to you, as well," Cosmic smiled, giving her a quick peck on the cheek. But Luna wasn't satisfied with that, and gave him a kiss on his lips before she retreated back into her room.
Cosmic's smile grew wider, even as the guards watched in confusion.
"Hello, Cosmic."
The stallion in question turned to find Celestia looking down at him with a neutral expression. "Good morning, Celestia. Is there something on your mind?"
Celestia scrutinized him with every ounce of effort she could muster, tried to find out what his master plan was just by staring into his silver eyes. But no matter how hard she looked, she just couldn't find any malice in him. She contemplated what this might mean, then came to a startling realization:
He was innocent, and she was biased.
She tried to deny it; tried to convince herself that he was, in fact, doing this on purpose. But in the end, it only made her frown at herself for trying to throw someone else under the wagon for what Luna was doing.
But still, there was the reality that Luna was, in fact, beginning to change, and Cosmic was at the center of it. If something wasn't done about it, and soon, she might lose her sister again.
So Celestia sighed, "Take care of Luna, Cosmic."
He raised an eyebrow. "Is something wrong?"
She shook her head. "Just an old mare being concerned for her sister, that's all. You're clearly a good stallion, but you seem to bring out old tendencies in Luna. Please... just don't let her do something she'll regret, okay?"
He nodded. "As long as I'm able, no harm will ever come to Luna."
Celestia smiled wearily. "That's all I ask."
With that, she left to raise the sun, leaving a contemplative Cosmic behind.