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Gerson's Lullaby

Summary:

A small wail slips through the quiet waters, a baby's cry becomes a fathers lullaby.

Notes:

I love Gerson Boom and his son Alvin so much mwa mwa mwa, I made this heartfelt one shot about a (slightly younger but still old) Gerson as a first time Father. (This story takes place more in Undertale's world, before the barrier was opened.)

(See the end of the work for more notes.)

Work Text:

The Underground’s moonlight pooled through the window of the Boom Residence, gently illuminating the room in a soft crystalline glow. Gerson and his wife Marka lay spooned together beneath a thick woven blanket—her tail draped between her snoring husband’s legs. Gerson could feel the slow rhythm of his wife’s heartbeat, it was warm and grounding. The gentle warmth of their breaths rising and falling in a shared rhythm and for a moment, everything was quiet and peaceful…

Then, a sound broke through the peace with the subtlety of a sword unsheathing, it was gentle—barely broke above a whisper, but still, it was beckoning. It was the tiny, quavering wails of the newly hatched son, Alvin, he was just over three months out of his egg at this point. Gerson blinked his tired eye awake, his vision was clouded from the dark. He let out a rasping sigh that was half laugh, half groan. “Heh…already got the lungs of a warrior, little fella does.” His wife Marka didn’t stir, she did however snuggle herself deeper into the blankets with a muted, unconscious grumble. The olive scaled monster sighed through his nostrils, it was his turn again to take care of the hatchling.

The crying continued, wheezy but piercing. Gerson pushed himself up and slid carefully out of bed, mindful not to disturb his Mrs. Boom. He shuffled toward the fatigued whimpers. Inside the crib carved lovingly out of the cedars from Snowdin by Gerson himself, laid the not so sleeping baby. He was partially wrapped in a sea-green cloth and kicking with surprising strength for something so newly hatched, most of the fabric broke free from his limbs, his little claws flexing desperately for comfort.

“Shhh now, little Alvie.” Gerson whispered, scooping him up with a practiced gentleness. Little Alvin wiggled and cried, his soft shell barely bigger than his father’s palms. “Easy lad, let Mama have her rest,” He purred, exhaling a long, fond sigh. “C’mon, little soldier, let's get you sorted, aye?” he rocked Alvin in his arms, careful, melodic, cradling him close. The hatchling only quieted a little, hiccuping as the older man carried him into the next room—a cozy nursery with a rocking chair, a bioluminescent lantern, and shelves lined with books and tiny blankets Marka had fussed over. Gerson moved with surprising tenderness for someone who was second in command in the legendary Human-Monster War, he nudged the door mostly shut with his tail, muffling the cries of his son from reaching the bedroom.

Alvin squeaked impatiently, waving his stubby arms. “Aye, aye, I hear ya.” The tortoise chucked tiredly. “Ya got lungs strong enough to frighten a Moldsmal.” He continued lightly bouncing the infant with one arm while rummaging with the other, retrieving a bottle of milk warmed earlier and wrapped in a specially made heated cloth from Hotland to keep it from cooling. “There we are…almost ready…” The tortoise murmured, shaking the bottle gently before guiding it to his son’s tiny mouth. The moment the bottle touched against his beak, the crying quieted into soft, eager suckles. Gerson felt his whole chest warm at the sight. Alvin sniffled, hiccuped, and latched onto the bottle with one hand, while the other wrapped around his fathers fourth digit—the pinky. Gerson giggled. “Aha, so that’s what all the fuss was about, huh? Not seeing your Old Man?”

Alvin's head bobbed against Gerson’s chest, his suckles faded into sleepy gulps, then tiny contented snuffles. The soft suckling sounds filled the quiet as Gerson lit a lantern low, bathing the space in gentle amber. He settled into the rocking chair, Alvin tucked securely against his chest. Gerson rocked slowly, his tail curling around the chair's slats, and after a moment he began to hum, low and unsure—before letting a melody unfold.

It was a song he had sung once to one of his frightened comrades during the war, to steady their spirits when the darkness felt too near. His voice softened, his last memory of watching them as the Barrier closed all those years ago replaying in his mind like a broken record. In his mellow, rasping voice it flowed like a lullaby, softly...slowly, in a voice gentle as his mother's used to be when she sang it to him as a young sprout. The old man's voice roughened by years, but tender as the tide…letting the humming evolve into a warm carol.

 

“Too-ra-loo-ra-loo-ral…
Too-ra-loo-ra-li…
Too-ra-loo-ra-loo-ral…
Hush now, don’t you cry…”

 

The lullaby drifted through the room like a warm current, wrapping the moment in something ancient and comforting. Alvin’s tiny claws relaxed. His tail curled around Gerson’s wrist. The tortoise felt his heart ache—not with sorrow, but with a deep, sweet fullness he hadn’t felt in years. The baby sighed, completely at peace. And for a while, in that small room lit by soft crystal glow and quiet love, Gerson let the rest of the world fade away.

 

"Back before the army, many years ago...
My mother sang a song to me, in tones so sweet and low...
Just a simple little ditty in her good old fashioned way...
And I'd give the world if I could hear that song of hers today..."

 

As Alvin drank, his eyelids grew heavier, blinking slow and dreamlike. Gerson rocked him gently, letting instinct guide him. Alvin’s eyelids drooped, the last bits of fretfulness melting away as the lullaby wrapped around them. Gerson continued until the last flutter gave way to peace, and the final verse whispered into silence.

 

“Too-ra-loo-ra-loo-ral…
Too-ra-loo-ra-li…
Too-ra-loo-ra-loo-ral…
That's an Old Man’s lullaby…”

 

“There we go, good lad...” he murmured, pressing a gentle kiss to the hatchling’s forehead as he let out a tiny, contented trill and drifted fully into sleep. “Sleep well, little Alvie,” he whispered, “Your old man’s right here.” Gerson kept rocking even after Alvin slept, savoring the quiet. And in the soft glow of the lantern, father and son drifted together into a soft, safe silence—while Marka snored blissfully unaware in the next room.

 

~

 

Morning crept gently into the nursery, not with sunlight—but with the slow brightening of the glow-crystals lining the walls. Their pale cyan shimmer settled like a hush over everything, illuminating the quiet shapes of blankets, bottles, and a very exhausted turtle slumped in a cushioned chair. Gerson’s head had dipped forward sometime during the night, his mouth hanging open in a faint snore. His arms still securely cradled Alvin, who was curled against him in a warm, gentle embrace. The hatchling’s tail flicked as he stirred. His golden eyes blinked open—round, bright, and curious.

For a moment he was still, then he spotted something marvelous; Gerson’s beard—long, faded pink, and wonderfully within reach. With a tiny coo, Alvin lifted both arms and latched onto the nearest tuft, gripping it with surprising delicacy. He didn’t pull hard; instead, he guided the soft strands toward his face, rubbing his cheek into them with sleepy satisfaction. A faint rumble escaped Gerson—half snore, half confused grunt. Alvin tugged again, very gently. Gerson snuffled once…twice…then cracked open an eye. “…Hrmm?”

He blinked down at the little bundle in his arms. Alvin beamed up at him, still holding a handful of beard like it was the softest treasure in the whole Underground. “Ohhh, lad…” Gerson rasped, his voice thick with sleep and fondness. “That’s one way t’wake yer old man.” The hatchling squeaked happily, nuzzling deeper into the pink and cream tufts. Gerson chuckled—deep, warm, and a little embarrassed. “So I didn’t make it back t’bed after all, aye?” he muttered, rubbing the back of his neck with his free hand. “Can’t say I’m surprised, chair’s softer than it looks, eh?” Alvin only cooed, tugging the beard again in gentle greeting. Gerson leaned down and pressed his forehead lightly against the baby’s. “Aye, good mornin’ to y’too, Alvie.”

For a quiet, precious moment, they stayed like that—the shelled monster, bleary-eyed but smiling, and the hatchling who seemed perfectly content to greet the day by clinging to his father’s beard.

Notes:

I hope you liked this fluffy corny one shot! I have a lot more Boom related fics on the way! (Marka is a Headcanon name I've coined for Ms. Boom to actually give her a character because I love her too, we need more Boom family apreciation pieces. This is part of a collection but is a stand alone piece not connected to anything specific, so don't worry, you didnt miss anything to get to here!) [btw that song is real, just changed the lyrics a bit]

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