"Uh, hello...What are you doing in my storage closet?" The voice she had heard had been this...this colt version of herself. Crawling out of the dusty little room, Twilight unleashed a few more explosive sounding sneezes.
"HaaTCHOO! HaaaaaTCHMPH!! HaTCHMPH!!" Stifling them seemed to do little to damper the extremely loud sneezes. The colt Twilight backed away slightly.
"Are...Are you okay?" She nodded, rubbing her snout a bit sheepishly. He levitated over a box of tissues. "Jeez, I didn't think anypony else had sneezes that loud..." Twilight smiled.
"They don't."
"What?" The colt version of her looked at Twilight incredulously.
"The nature of certain involuntary actions of unicorns is based primarily on the level of magic in their reserves," Twilight explained, "Therefor, actions such as sneezing, coughing, or hiccuping are more accentuated or frequent in ponies with large magical reserves. Such actions are often used to measure a unicorn's magic, but they are not completely accurate, and give only a suggestion. No actual measurements. Such a thing has always been present in unicorns."
"I'm afraid I don't understand. You are just also a very powerful unicorn, or at least, that's what I'm getting out of this..."
"You, Mr., are the Element of Magic, correct?" A nod. "And thus, having such magical capabilities to be able to wield the Element must mean that only the Princesses could possibly match or go over your limits. So how could another pony have as strong of sneezes as you if you should be the only mortal pony with such magical strength?" The colts eyes widened.
"Wait a minute... Are you saying...?"
"I am Twilight Sparkle. Student to Princess Celestia and wielder of the Element of Magic." She struck a regal pose, trying to sound as though she hadn't just been hiding in his closet. The image, however, was interrupted with another explosively loud sneeze. "HaaaaTCHMPH!!"
"Bless you..." He paused, "Twilight Sparkle." He looked her up and down fora moment before continuing. "I am Dusk Shine. Student to Prince Solaris and wielded of the Element of Magic." He sat down on his haunches. "Wow...Where did you come from?"
"I came from another....ano-...anahh-....haaaaaTCHMPH!! Excuse me..." Twilight blushed, "I came from another universe."
"Do they...not have dust in your universe?" The crimson tint in Twilight's cheeks deepened.
"Allergies." Dusk snorted at this.
"You live in a library. You have to dust the books. Isn't that hard on you?"
"Well, it isn't usually a problem with the dust, but I was in this really musty place earlier today, it was probably rotting, and it got to me." Dusk was nodding in understanding.
"Oh, I see. So now everything bothers it?" Twilight nodded. "Well, then I suggest taking a shower. You're covered in dust." Twilight blushed even deeper and tried to shake some of it off, only achieving a dust cloud around herself and Dusk.
"HaaaaTCHMPH!!" Twilight covered her snout with her hooves to cover the sneeze and realized she hadn't been the only one. "HaaaaaaaaTCHMPH!!!" Dusk's eyes had tears in the corners and he was rubbing his snout with a tissue.
"Heh, this usually doesn't happen..." he said, blushing.
"I know. That's what I was just telling you."
"Right, so...I expect that you can find the shower? I'll let you go first." Twilight nodded.
"Thanks, it'll be good to get some of this dust off of me, though I'm sure the shower won't be too easy on my sinuses either... Oh well." She trotted up the stairs to the shower. Dusk smiled, watching her go, and started up the stairs a minute later. He wanted to hear if she was going to have the same water difficulties as he knew he would today, or maybe even worse. She sounded like she'd been sneezing like that for a while. Dusk knew how that felt...bad.
After a long time, which consisted mostly of trying to stifle sneezing while the shower was running, Twilight emerged from the bathroom with a soft, clean coat and perfectly organized mane. Dusk took in the image of...himself. Wow. He looked pretty good as a mare...
Twilight waited in the library as Dusk showered, but her deprivation of magic reserves seemed to sap the remaining energy she had. She laid her head down on the floor of the library and was snoring softly by the time Dusk came back downstairs. "Wow...she must've been exhausted. Casting a spell like that must really wear you down. I wonder if it's in any of my books..." The studious colt sat down and started going through his spell books, hoping to find the one that mentioned such a spell.