Author's Note: don't try what's in this chapter at home, kids, you can actually hurt yourself doing it.

This chapter is also out of chronological order; it takes place before the Infiltration chapters as well.

Much thanks to Aroaceaaah once again for the idea of Drell having the whole bifold vocal cord harmonizing thing, as well as helping me with Irish language while I was developing Drelleian noun classes!

"Hey."

Mordin glanced up from his reading. "Shepard."

"Got a minute?"

Mordin leaned back, tapped the display off, and nodded. "How can I help?"

Shepard leaned onto his worktable, resting her elbows on the hard surface. "Can you teach me more Drelleian?"

Mordin tilted his head to one side. "Certainly. Not late, though," he said, teasing; it was about midday, and she rolled her eyes good-naturedly.

"Yeah, yeah. I'm just curious." She winced. "That, and Thane asked me if I'd been practicing."

"Have you?" Mordin inquired, and Shepard winced even more. "Ah."

"Hey, you've had me learning Covus," she said defensively. "And Covus is hard."

"Complex," Mordin agreed. "Very well." He tapped the display once more, and it lit up; Shepard caught a flash of Covus script before he cleared it, popped out a stylus, and began to write.

"What were you reading?" she asked him, resting her chin in one hand.

"Writing," he corrected. "Book."

She paused. "You're writing a book?"

He flashed her a smile before returning to scribbling on the display. "No. Translating."

"You're translating a book," she clarified, her head bobbing as she spoke. "What book?"

"Catch-22."

She paused again. "Isn't that some old classic?"

"Twentieth century. 1961."

"Why are you translating a book written so long ago?"

Mordin stopped writing and leaned on the table, looking pensive. "No Covus translation available. Good book. Thought-provoking, if difficult, read." He shrugged. "Would like to send to nephew."

"Doesn't he have a translator?" she asked curiously, and he reached up and flicked her gently on the forehead.

"Information lost," he told her, and she grinned.

"Yeah, yeah. Okay." She shifted her weight from one foot to the other as Mordin began to write again. "How's it coming?"

"Mm… difficult," he admitted, not looking up. "Author claimed wouldn't translate well into other languages once - was partly correct. Complex concepts, circular logic, nonsensical logic." He shrugged. "Challenging."

"Circular logic?"

He nodded. "Ever read book?" She shook her head as he handed her the display. "Term catch-22 coined - rule in which terms fulfilled nullifies initial terms."

"Terms fulfilled?" She took the display and surveyed the information on it: instead of the usual tense chart, he had written what appeared to be a pronunciation guide.

"Such as, in order to get job, must have experience; cannot get experience without job."

"So, like a paradox," she supplied, and Mordin inclined his head. "What's this? I already know the pronunciations."

"Grammar," he said, shaking his head. "Noun classes."

"Oh yeah - like, the eryu and iryä tense thing, right?"

Mordin leaned forward and rapped her on the forehead, and she yelped. "Not tenses! Noun classes. Tenses for time, with verbs."

"Okay, okay! You don't have to whack me on the head about it," she grumbled. "Noun classes. So there's eryu and iryä, and - what's the third one?"

"Iryäy," he said. "With ay on the end. Rhymes with tie."

"Iryäy," she repeated. "I thought you said there were only two - eryu and iryä."

"Third - iryäy - is derived from nouns, but not exclusively nouns - not technically noun class."

"Ah." She tapped the display absently. "So - is most of this pronunciation?" she asked.

Mordin pointed to the first column. "Pronunciation and spelling - some more akin to vowel mutation. Change in vowel sound indicates change in grammatical function, definition." He paused. "Better-known example - consonant mutation in human languages. English, seek, sought, think, thought. Or Irish, maith, an-mhaith."

"An-what?"

"An-mhaith." Mordin tugged the display from her and scribbled the word in the corner of the screen. "Pronunciation very different from apparent English spelling - H changes pronunciation of m."

She took the screen as he handed it back, and squinted at the word. "Is that really how it's pronounced? It looks like may-th."

He rapped her on the forehead again, and she huffed. "An-mhaith, said like an-wah," he corrected. "M becomes w, 'th' softens to voiceless."

"An-mhaith," she repeated. "How do you even know that?"

"Worked with more humans than just you," he teased, then tapped the screen, and she surveyed the display.

"Is the biggest difference just accent marks?"

Mordin leaned on the table, one arm outstretched and tapping idly at his omni-tool. "Accent - in English script, umlaut - marks shift from eryu class - physical, tangible objects - to iryä, intangible. Y added marks shift from iryä to iryäy."

"What exactly is the iryäy class? You didn't mention that one before."

Mordin leaned back and examined his omni-tool. "Complex class," he began. "Metaphysical, of sort - example: physical item is person, eryu; conceptual equivalent is identity, iryä; metaphysical equivalent is self-awareness, sentience, iryäy."

"Seems straightforward enough," she mused, then frowned as he gave her a smile.

"Not very. What would iryä of 'piece' be?" he asked.

"Uh - conceptual piece, so… the idea of a piece, or a fragment?"

"Good. Step further - iryäy."

She paused. "I'm guessing it's not just the concept of the concept," she said, and Mordin shook his head. "Maybe… something that's broken?"

"Would be eryu, then - physical thing," he said.

"Oh. Right." She frowned again. "Maybe… the element of fracturing? Conceptually?"

"Close," he said with a nod. "Element or state of being incomplete, fragmented." He checked his omni-tool, then glanced back to her. "Scale?"

"What?"

"Iryä of scale?"

"Oh. Scale is tat, so that would be…" She consulted the table. "Tät? Uh…" She stared at the display. "Well, that's skin for a drell, so… I don't know, barrier?"

"Not quite. Word doesn't exist in English - concept of space occupied, limitation of personal existence, limit of proprioception." His omni-tool faded, and he steepled his fingers. "Now iryäy of that?"

Shepard winced. "Ah."

Mordin shot her a grin again. "Iryäy of that doesn't exist in English, either - concept of limit itself, limit of understanding, of awareness." He made an odd face - the skin between his nostrils wrinkled in a grimace. "Difficult to understand - salarian, not drell. Difficult to conceptualize."

"It's a really abstract language," she observed, and Mordin nodded, leaning on the table again, his hands splayed across the white tabletop. "How'd you learn it?"

"Music, poems," he answered honestly, rocking on his heels. "Gorgeous poetry. Initial interest in songs."

Shepard perked up. "Songs?" she asked, and Mordin chuckled.

"Abstract language, abstract poems, songs," he said with a nod. "Many use relation between tangible, intangible, and metaphysical to create theme through verses."

"You know I'm going to ask you to sing," she informed him, and he inclined his head.

"Wrong pitch," he said simply. "But will, if you like."

"Of course."

"Why not ask Thane?" Mordin asked curiously, tapping open his omni-tool again and scrolling through text, and Shepard shrugged.

"He'd demand I translate it." Mordin paused; Shepard groaned. "And now because I said that, you're going to make me translate it too, aren't you."

"Why not?" was the answer; Mordin flexed his fingers and Shepard saw a flowing text scroll across his palm. "Good exercise."

"Because I still don't know enough," she complained. "And you've gone and added a whole 'nother set of nouns here."

"Derivational," he stated. "Exercise critical thinking. Ah." He held up his omni-tool, and Shepard could see verses layered across his palm. "Jäyl aiks häl."

"Okay. Uh - hal means injury, so häl would mean… pain or something? What's jäyl?"

"Jal - life signs, jäl - life, jäyl - existence."

"So… 'Existence is pain?'" She snorted. "That's a little dramatic, isn't it?"

Mordin held up a finger, the orange glow of his omni-tool glancing off the work table. "Not just pain," he corrected. "Concept of hurt, damage caused - akin to saying, 'existence is to endure injury.'"

"Still sounds dramatic."

"But poetic," Mordin reasoned. "Song about finding refuge in another, shelter from life together. Very heartfelt."

"Huh." She leaned one elbow on the table, her chin in her hand. "Are you going to sing it?"

Mordin tapped his omni-tool once more, scrolling through the verses. "If you wish," he replied, then flicked his fingers; the display in her hands lit up with the curvy script she'd seen overlaid on his palm, and she handed him the display.

"Omni-tool too small?" she asked, and he shrugged.

"Easier to see." He leaned back, eyes roving over the display, then he began to sing, a low, somber tune. "Jäyl aiks häl, n'esse; nitoi näy raus hyl tat e nuu, teiks näy jalvyo e nuu…"

As he sang, Shepard nodded slowly; the language's vowel pronunciation sounded vaguely Nordic, but the accent Mordin adopted was far more fluid and soft.

The salarian began to rock on his heels, eyes half-closed as he sang. "Jäyl aiks häl, n'esse; nitoi näy raus hyl tät e nuu, teiks näy jälvyö e nuu…"

Shepard filed away the words she recognized - some she recognized only because she knew its eryu counterpart.

"Jäyl aiks häl, n'esse; nitoi näy raus hyl täyt e nuu, teiks näy jäylvöy e nuu…"

She tried to pay attention to the words; the tune was almost hypnotic, though, and she leaned more heavily onto the table. "It's pretty."

"It's flat," said a deep, mild voice right behind her, and she stifled a yelp; Mordin's eyes twinkled, and she stuck her tongue out at him before turning.

"I didn't even hear you come up," she accused, and the drell shrugged, palms wide in a nonchalant gesture.

"I overheard, and decided to investigate," Thane said lightly, linking his hands behind his back, then glanced to Mordin. "Your rendition was…" He paused, and Mordin covered his mouth with one hand, eyes amused.

"Lacking?" Mordin asked, though seemed to find the prospect more amusing than offensive.

"Interesting," Thane stated. "I can't say I've heard half of a häisii in that octave."

"What?" Shepard glanced between the two aliens, both of whom were grinning to each other. "Häisii?"

"Song characterized by self-harmony," Mordin explained. "Drell vocal cords quite different - bifold vocal cords, creating resonance." Thane hummed in agreement, the sound echoing through the tech lab. "If careful, can harmonize with oneself."

"Typically in much lower tones," Thane added, his voice even, and Mordin hid a smile behind his hand again.

"Am I missing something?" Shepard asked suspiciously, and Thane shrugged.

"Merely remarking on his rendition of jäyl aiks häl," he said reasonably. "Not bad, for…" He trailed off.

"For…?" continued Shepard, leaning on the worktable again, and Mordin chuckled.

"For salarian," he supplied, and Thane winced, though nodded.

"Mordin's singing is fine," Shepard said, somewhat defensive, and both aliens held up their hands in a conceding gesture.

"Never said it wasn't," Thane assured her. "Merely sounds a little, er…"

Mordin muttered something that sounded suspiciously like helium, and the drell snorted.

"A little chipmunk-y," Thane finished.

Shepard gave a rather undignified snort and glanced over to Mordin, who had an odd, thoughtful look on his face. "Chipmunk-y?"

Mordin said nothing, and merely gestured to Thane, who turned to the Commander and inclined his head.

"Picking up where he stopped…" Thane said gallantly, and began to sing the same tune. "Kal näy nuu ki, kal näy jäylvöy pyin tät däl räya hyi au tata hyl val näy. Kal näy nuu ki, kal näy ra pyin räy däl räya hyi au täta hyl jäip näy."

His much deeper, more resonant voice gave it a haunting quality - making Mordin's sound indeed a little chipmunk-y in comparison - and the harmonization that Mordin mentioned created a reverberating, thrumming feeling in her chest. "Wow. I can feel it."

Thane placed one hand over her chest, not touching, but merely hovering his hand over. "Rähäis," the drell told her. "We call it soul-music."

"I don't think your rendition was bad, though," Shepard said, turning back to Mordin - only to frown. "Where'd he go?"

"Engineering, I suspect," Thane said speculatively, and Shepard raised one brow.

"Why?"

Thane didn't respond, and merely blinked at her slowly, a slight smile on his face; Shepard rolled her eyes and grabbed the display left on the worktable, then began to scroll through the verses, trying to pick out words she recognized.

"'Existence is pain,' uh - what's n'esse?" she asked.

"My dear," Thane answered.

"'Existence is pain, my dear; follow the…' Ugh, I really don't know enough to translate this," she grumbled, and Thane delicately took the display from her.

"'Existence is pain, my dear; trace the curve of my scale, outline my veins; existence is pain, my dear, trace the curve of my soul-scale, outline my lifeblood,'" the drell translated. "'Existence is pain, my dear; trace the curve of my soul-print, outline my soul; bring me down, bring my soul from its soul-scale to rest on the scales of your hand; bring me down, bring my body from its rest to rest on the soul-scale of your mind.'"

"Soul-scale?" she asked as Thane set the display back on the worktable.

"Conceptual segment of one's soul," Thane explained, linking his hands behind his back again. "Iryä of scale."

"Huh. So - when you say lifeblood, that's the iryä of veins?" she asked, and he nodded.

"Outline my veins, outline my lifeblood, outline my soul," Thane said gravely. "Trace the curve of my scale, the curve of my soul-scale, the curve of my soul-print."

"So that's like… jalvyo, vein, then jälvyö, lifeblood, then… Jäylvyöy?"

"Jäylvöy," came a very unfamiliar, very strangely-pitched voice from behind her; startled, she whipped around, one hand coming up and lashing out; Thane stepped forward, one hand raised, but not before the heel of her palm made solid contact with Mordin's jaw.

The salarian let out a shocked hmph! noise, stumbling back; blinking, his eyes watering, he fixed his gaze on Shepard, who had flung both hands over her mouth.

"Mordin!" she exclaimed, and reached one hand toward him; he waved her away, eyes still watering. "I'm sorry, I didn't realize! It didn't sound like you!"

Mordin paused, then his face suddenly broke out into an almost terrifying smile, and Shepard froze, while Thane made a strangled, choked-off noise in the background.

"Mordin?"

"Yes?" Mordin asked, looking innocent as a summer sky - only, he didn't sound like himself at all. Instead of the neutral, careful, slightly-higher-pitched-than-human tones she was used to, his voice sounded like it had been run through a cheap low-pitch filter and then played underwater. She gave an awkward, hesitant laugh.

"Uh, excuse me, Mordin, but what?"

"Sulphur hexafluoride," Mordin boomed, the bizarre, artificially-lowered pitch to his voice causing him to sound like a knockoff circus announcer, and he gave another innocent smile and waved what looked like a small canister with a whistle valve fitted onto one end. "Six times denser than air; sound propagates more slowly; hence, deeper voice." He leaned back and sucked in a deep breath, then exhaled, then breathed in again; when he spoke, his voice was mostly back to normal. "Sulphur hexafluoride also used as arc suppressant. Nicked from engineering; have plenty." He tucked a hand into his pocket and drew out another canister; delicately, he put his lips to it and breathed in, then cleared his throat. "Helium six times as light as air," he squeaked, the helium making his already-high voice nearly hit the upper limit of comfortable hearing range. "Helium used as coolant for superconductors."

Shepard paused, her face half-frozen in a bewildered grin. "Mordin Solus, what the fuck?"

"Hm," Thane said pensively, holding out a hand; Mordin gave him the helium canister, and the drell took a breath in, then handed the canister back. "Hello," Thane said hesitantly, and Shepard couldn't help it; she burst out laughing. The drell's voice had pitched up to nearly human range, and sounded very artificially pinched.

Mordin took several breaths again to clear the gas from his lungs, then inhaled from the sulphur hexafluoride again. "Peculiar experiment," he said, his voice pitched down comically low; Shepard merely laughed harder.

"I want you two to sing like this," she gasped. "Please."

Mordin exchanged glances with Thane; he gave a tiny incline of his head, and began to hum.

Thane chuckled, the noise sounding artificial and tinny. "Interesting song choice," he remarked; Mordin merely held out the helium canister, and Thane took it gently.

"Limited verses," Mordin warned. "Dangerous to inhale too much." He put the whistle end of the sulphur hexafluoride canister to his lips again and inhaled as his voice began to pitch back up to normal; Thane did the same, and Mordin began to hum again.

Shepard hastily fumbled for her own omni-tool, then clicked the record button as Mordin and Thane began to sing in unison, the combination of pitched-up-drell and pitched-down-salarian creating a hellish sound straight out of a children's nightmare.

"Those poor unfortunate souls!

So sad, so true;

they come flocking to my cauldron

crying, "Spells, Ursula, please!"

And I help them!

Yes I do!

Now it's happened once or twice,

someone couldn't pay the price

and I'm afraid I had to rake 'em across the coals;

yes, I've had the odd complaint,

but on the whole I've been a saint

to those poor unfortunate souls!"

Mordin finished with a flourish, giving a bow; Thane tilted his head forward more demurely.

"Oh hell," Shepard gasped, clicking the pause button on her omni-tool and wiping one eye. "Oh my sweet stars, you two," she managed, still laughing. "Mordin, what the hell!"

"Fun trick," Mordin said, eyes twinkling with amusement, his voice back to normal. He collected the helium canister from Thane and clicked the whistle-valve end of each of them shut. "Do wonder what jäyl aiks häl would sound like with that, though."

Thane winced. "Perhaps when I am not in the room," he rumbled, and Mordin chuckled.

"Goes for you too," Mordin told him lightly, though the drell gave a small shake of his head.

"I prefer traditional häisii," he said ruefully. "Apologies, but I think it would make my head hurt."

"Aw, come on," Shepard said jovially. "Maybe Mordin could get his voice pitched low enough to sound proper."

"Quite artificial," Thane replied, interlocking his fingers, then glanced to Mordin. "No offense."

"None taken," the salarian said cheerfully.

"I should get back to my walk," Thane said lightly, releasing his hands and clasping Shepard on the shoulder, then nodding to Mordin. "Thank you, though. That was quite amusing."

"Of course," Mordin answered, tucking the two canisters onto a shelf on his desk. "Oh, and Thane? Have upgrade for rifle. Please see me later."

"I will." With another incline of his head, the drell wandered off.

"More Drelleian, or work?" Mordin inquired as Shepard pushed away from the table.

"Work, probably, but - wait," she said quickly. "Mordin, can I borrow the sulphur hexa- hexa-whatever stuff?"

Mordin raised an eyebrow. "Can be dangerous," he said reproachfully, but Shepard shook her head, a wide grin blossoming across her face.

"I just want to do one thing. EDI, can you make sure Joker isn't working on anything crucial?"

"Of course, Shepard," answered the AI.

"Ah," Mordin said knowingly, shaking his head.

"Don't want me to?" Shepard asked, but Mordin chuckled and merely handed her the canister.

"Only one breath at a time," Mordin told her, and flicked the valve open again. "Careful."

"Of course," she told him breezily, then inched toward the door. "I'll bring it right back," she told him with a mischievous grin, then ducked out the door.

Mordin watched her go with a wry smile, then sat back and waited.

"LUKE, I AM YOUR FATHER!" Shepard's artificially-lowered and very loud voice boomed through the comms, and Mordin heard a high-pitched screech from the helm, amidst clattering and thundering as what sounded like the entire ship's crew jumped about a foot in the air.

"SHIT - that wasn't supposed to go through the comms!" came Shepard's low, panicked voice. "Sorry, hold on - " There was a panting as she tried to clear the gas from her lungs. "I'm sorry, that wasn't supposed to go through the comms! It's just me, it's just me!"

Silence; then, Mordin heard a roaring of laughter echo throughout the ship, and he shook his head ruefully, and began humming as he flicked open his translation again.

"Poor unfortunate souls…"

Author's Note: Fun fact, during writing, this chapter was affectionately and informally nicknamed "the chipmunk chapter."

Drelleian is turning out to be a really fun language (at what point am I going to stop saying "this is a really fun language!"? probably never). The whole tangible/intangible/metaphysical class series means there's a TON of words and grammatical shifts that just don't exist in English at all. It took me days to write that song and it's still pretty basic verse. The pronunciation shifts were inspired pretty heavily by Irish's initial mutations - while Drelleian noun classes have vowel changes, not consonant changes, the concept is still pretty much the same in that it indicates grammatical function through spelling and pronunciation.

Catch-22 is a bizarre book. It's difficult to read, too, from a reading-comprehension standpoint, but also a "this shit's really fucked up" standpoint. From a cognitive aspect, it's pretty interesting, though.

Sulphur hexafluoride is indeed the "opposite" of helium, and it sounds REALLY wacky! Search it on Youtube, there's a good video of Adam Savage (the Mythbusters guy) demonstrating it.

"Poor Unfortunate Souls" is probably recognized by most, but in case it isn't, it's the song Ursula sings when she cons Ariel out of her voice in The Little Mermaid.