This story is exactly how the description states: basically a style with the basic plot of The Great Gatsby with Undertale characters. It's not an exact AU, but I guess it technically could be called one.

i got this idea after my best friend jokingly called Gaster "The Great Gaster" in reference to The Great Gatsby and as a result this story was born. It'll contain a few OCs, but of course it's centered a lot on Gaster, too. It'll contain quite a few people that are, in a way, my Undertale equivalents of characters in The Great Gatsby. A couple are obvious. Others... maybe a little hard to distinguish. Can you guess who's equivalent to who? :)

Just FYI, this isn't going to have the same exact plot as The Great Gatsby. I'm taking a few creative liberties with it because I want this story to also be unique. Some character personalities might be different than those of the TGG. It's intentional because I want my characters in this story to be likable. It's also not going to have a lot of the current UT characters because it's about Gaster so it takes place before Frisk and the others. However, that doesn't mean other characters won't show up as the story progresses in its timeline ;)

Anyway, please leave a review! It might not seem like much at first, but I have great plans for this story, especially during the middle and end. It'll also answer a lot of questions about Gaster like how he got erased from time, etc.

Chapter 1: Royal City

My father once told me, "Whenever you feel like criticizing someone, just remember that you haven't experienced what they've experienced. Instead of scorn, try to understand where they're coming from." This is a statement I've tried to hold myself to. I like to think I'm a good man, but I admit that I, like anyone, am not without fault.

Sometimes I wonder if I had been too passive concerning my friend Gaster. He was a brilliant man, er… skeleton, but like myself and others he was not without fault.

I miss him though. He was one of the few friends I had. However, it didn't start out that way.

But before I go into a whole spiel of my friend Gaster, I suppose I should provide some background on myself.

My early childhood was happy. I grew up in a little house in a small family just outside Snowdin. I displayed an early interest in science, a passion my parents encouraged me to pursue. My family's household consisted of my mother, father, younger brother, and myself. I was the eldest child.

We were a small family of rather wide-eyed humanoids, at least that's the best description I can think of. As I child I barely knew what humans were, but now I know exactly what a human looks like and have come to realize humans and my family were not too different biologically. We stood and walked on two legs; we had two arms, two hands, and two feet. At first glance it almost seemed like we weren't that different, but there were differences.

The species of monster I was did not have hair and our skin was very different texturally. Human skin is so smooth and fragile, easily damaged. Our skin was smooth, but tougher. I didn't have scales like the reptilians, but I wasn't so delicate, either. Our eyes were also much wider than a human's, as well as perfectly round. We weren't generally inexpressive, but we often looked that way. In fact, other monsters have humorously called me a master of the "blank look." I find it amusing because it's true.

My whole immediate family was orange in color except myself. I was a golden yellow, a trait apparently inherited from my grandfather.

Though my childhood was happy, I can't quite say the same for about half of my teenhood. My parents died when I was fourteen and my brother only six. We were then placed in foster care. It wasn't bad, but it couldn't be called fantastic, either. When I reached early adulthood, I found it a silly idea to continue living with my guardian, so I actively searched for a job and a place of my own.

It was an unusually warm day for Snowdin when I spotted an ad in the local newspaper stating that the royal scientist W. D. Gaster was looking for a helper. "Must be interested in and show potential for a future career in scientific endeavours," I read. "Any previous background in science is a plus, but not absolutely necessary. Any monster of any status can apply."

A warm wave of excitement passed through me and a whirlwind of questions filled my mind. THE Gaster? Gaster the royal scientist? He's looking for help? And anyone can apply?

I didn't idolize Gaster as much as some, but I did have a great admiration for him. He'd been talking about building some type of machine that if successful, might revolutionize electricity for us monsters. Few details were released, but if I remembered correctly Gaster had said it could bring electricity to every monster house in the Underground. I had studied electricity and loved the idea of it, but alas I didn't have it growing up.

I couldn't help but feel I may have a good chance at this job. Few monsters had scientific ambition in the Underground. There was only one royal scientist after all, and that was Gaster. The only monster I even knew about with a passion for science was myself. I had read every science book in the Snowdin library at least five times, maybe more. I even liked to consider myself an amateur scientist, though I had held no official job with that title, or any title really.

I might actually have a chance, I couldn't help thinking rather confidently, so I got to work. I filled out an application and sent it to the royal palace through the mail. I waited anxiously several days, answering the door every time the doorbell rang. My brother often watched me in amusement.

It was maybe two weeks later when I received a response. I snatched the letter out of the postman's hands, perhaps a little too roughly, and ripped it open.

My normally neutral expression wasn't passive at all. A grin was gracing my features as I read over the letter. "What's gotten you all smiley?" my brother asked from his seat on the couch.

"I was called in for an interview. Next week," I murmured. I eyed my brother. "Just think," I began. "I'm going to meet Gaster himself."

"Nice," replied my brother absentmindedly. He wasn't really paying attention now, but I didn't care. I rushed into the room I shared with my sibling and frantically began to write a reply letter.

The next week twenty-four-year-old me was making the trek through the Underground to the royal castle. As always I first travelled through Snowdin, my homely little town. I shivered and pulled my coat closer, my feet crunching cross the snow. The air smelled like cold and snow, a smell I was very familiar with. It was snowing the day I left, not unusual at all. I had already bid goodbye to my brother and guardian.

My guardian was a kindly, middle-aged woman who cared deeply for me and my brother. She was a small, brown, rabbit-like monster. Though I was fond of her, I coudn't say I loved her like a mother or even an aunt. I doubt my brother did either, but I never asked, so I never knew for sure. My guardian was sad to see me go. She guessed I would be moving away if I got the job. I bid her goodbye a little sorrowfully but without any tears, hoping this would mark the next stage in my life.

I left Snowdin and entered Waterfall. The air turned from dry and cold to humid and just slightly chilly. A little sweat gathered on my forehead, so I unbuttoned my jacket. At first Waterfall was open with only a few small streams I had to walk over, but I soon found Waterfall had a cave system I had never encountered before.

The pathways grew dark and damp. I huddled closer into my jacket, not for warmth but more a sense of security. I had heard of the other Underground areas like Waterfall and Hotland, but as a child I barely left Snowdin. I had never been much of a traveller. At the present time I desperately wished I had thought to bring a map or at least ask for directions. Foolish, I scolded myself.

The caves had begun to make me feel claustrophobic. My journey started out wondrously. I had even passed a mysterious piano and an old set of armor singing a haunting melody. I wondered if the rain might have been hitting the metal in such a way that it sounded like music. Waterfall wasn't exactly giving me a great sense of security, however, so I didn't bother to investigate.

The cave system was like a dark maze. Crystals of blue and purple, probably lit by magic, dotted the pathways. The air was damp and stale, not exactly comforting. I tried to pay attention to specific patterns of crystals and directions of the passageways, but I was sure I kept going in circles. I managed to find a tiny town called Temmie Village. They were curious little creatures, a little like cats with hair, but not very intelligent. I asked them for directions, but they didn't seem to know how to get to Hotland. Sighing, I politely gave my leave and ventured back into the caves.

Hours must have passed that I didn't see a sign of anyone. My passive expression took on one of dread. Would I ever leave this place? Fed up, I groaned and sat back against the glowing wall. Using my logical mind, I considered my options.

Option one, wait for someone to find me. Not likely. Option two, search for a way out again. I've been doing that for hours. Option three, try to find my way back to Temmie Village. That seems the most plausible…

A sudden clink of something jerked me from my thoughts. Looking up, I craned my head to one side, listening for sounds. It clinked again. Sounds like metal, I thought. And voices. Excited, I sprang to my feet and hurried towards the sound. The crystals flew by like whizzing trails of blue light.

Three dark, yet silvery figures came into sight. They were talking to each other. There were two tall figures and a short one. The short figure walked very upright with its chest held high, giving off an air of importance. I guessed it was the leader.

Said figure caught sight of me quickly and suddenly stopped. Two green glowing… claws or… something, had appeared at its sides. They were like hands, but floating detached from the small figure's body. They stopped the figures following the short one and pointed at me. "Who are you?" demanded the small figure. "Speak."

I stood as tall as I could, not easy for someone like me who was just over five feet. "My name is Fidel… Fidel Amin," I stated. "I'm trying to find my way to the royal castle in… the Royal City." I suddenly realized how silly that name sounded. Wouldn't the king want to name it something more… astounding?

The figure's head twitched once and began to step towards me. Making its way to me, I finally got a clear look at it in the glowing light of the crystals. "Fidel… I know that name," remarked the voice. As the figure stopped in front of me I realized both its voice and figure were feminine. She was dressed in black under armor with silver plating over her chest, head, and lower legs. She didn't appear to have arms and I suddenly realized that those glowing green claws must have been her magical version of hands. Wide strings of metal hung from her waist and clinked against her legs as she walked, almost like an armored version of a skirt. Her visor on her helmet suddenly glowed green and flipped upward, revealing a pale green face with a small snout.

The woman was almost exactly my height. Her eyes had a friendly but serious look. She almost had a reptilian or maybe a dinosaur-like figure, but she stood straight upright like I did. "Ah, I remember that name," she asserted. "You're the Fidel who applied for position of helper to the royal scientist, aren't you?"

I nodded. "Yes."

She suddenly extended a green, magical claw in greeting. I shook it slowly. "I'm Sasha, captain of the Royal Guard," she said, studying me intently. "So, if you're supposed to be in Royal City, then what are you doing way out here?"

My face flushed. "Well... I got lost trying to find the Royal City."

She raised a brow. "Why didn't you just take the river ferry?"

"River taxi?"

She frowned. "You know, the ferry that the River Person runs. They gives rides to anyone who needs to travel quickly from town to town. The river runs all through the Underground, so it's perfect for speedy travel."

I found myself staring at the ground. "I've never heard of it before," I confessed. I imagined my cheeks were colored in embarrassment. "I'm not much of a traveller."

Captain Sasha eyed me with amusement. "I'm guessing if you don't even know about the ferry, then you don't know where you are, do you?"

I shrugged my shoulders. "I know I'm in Waterfall."

She chuckled and shook her head. "In that case, I will lead you to the city." She turned to the two figures behind her, who were completely covered in armor from head to toe, and spoke to them. "Buck! Arlo!" she commanded with an air of confident authority. "Make your way to the city on foot. All four of us won't be able to fit on the ferry together and I know you're familiar with way back. I'm going to lead Mr. Amin back to the castle myself. He needs to know about the river ferry if he's going to be travelling around the Underground." Her slitted visor flashed green a second time and slid down over her eyes. Her face was now obscured from view completely.

The two guards, Buck and Arlo I presumed, obviously respected their captain. They bowed and cried, "Yes, ma'am!" before sauntering off.

I was soon left alone with the captain, who gestured me in the opposite direction. "Come," she commanded with pleasant seriousness.

She led me through the caves without hesitation. I let out a quiet sigh of relief. Now I have someone who knows where she's going.

We began to descend down a dark passageway and I heard the faint sound of rushing water. The wall crystals soon disappeared and the passage grew more narrow. We walked only several yards before the air turned damp and the rocky ground beneath my feet was slippery with moisture. I almost lost my balance over the wet rock, but managed to regain my composure. Captain Sasha, however, seemed to have no trouble walking. I observed three long claws poking out of her shoes. They were a greenish tint like her skin, so I assumed they were natural. Perhaps they help with grip, I concluded. Either that, or she's just experienced walking over wet ground. Unless I asked, I wouldn't know for certain and at the time I wasn't feeling up for conversation, so I remained silent.

The passageway suddenly ended and I almost plunged forward into rushing water. Luckily the captain's "magical claw," as I had dubbed it, grabbed onto my jacket. Yanking me backward, the captain chuckled at my clumsiness.

"Tra la la. Don't fall in," sang a voice in front of me. I turned to see a cloaked figure studying us. Its face was completely dark and obscured beneath its hood. I saw no mask or visor that it might have worn. It was like the figure didn't have a face at all. "Where to?" it asked cheerfully.

"The Royal City," answered the captain. She bobbed her head politely, as if paying it a respect.

The River Person nodded. "Step in."

Captain Sasha let me step on first and she stationed herself behind me. It was a narrow fit, but we were both quite small, almost the same size. I was just slightly thinner, though I doubted I was anywhere near physically fit as she was.

The wooden boat, much like a small canoe, rowed steadily forward. "Tra la la. I am the riverman," sang the the hooded figure in front of me. "Or am I a riverwoman? Oh, it doesn't matter. I just love to ride in my boat. I'm happy to share my boat with others, too. Tra la la. Why don't you sing with me?"

The captain began to hum along with the River Person's tune. This hooded person had a sort of charm to them. I couldn't help smiling at the person's cheerful nature, whoever they were. I found myself humming along to their happy melody like the captain behind me was.

After a steady, peaceful ride that left me feeling quite serene, we arrived at the Royal City. "Tra la la, goodbye for now." The River Person waved farewell.

The city was breathtaking. Towers upon towers of buildings surrounded me, all bright in color. I was a small man and the buildings made me feel just miniscule. It wasn't the most brightly lit, but the city itself almost had a glow of its own. Monsters of all shapes and sizes busied about, buying supplies from shops and rushing to places who knows where. In the distance stood a magnificent palace that towered over the city itself. I felt smaller than ever.

Captain Sasha watched me with amusement. "It's amazing, isn't it?" she said.

I breathed in deeply. "Yes."

"Most monsters have been to the Royal City at least once in their life," remarked the captain. "It's rather funny to watch an adult man come to this place for the first time in his life."

I frowned. "I hardly ever traveled when I was younger."

The captain shrugged, or at least implied it, considering she had no arms. "Anyway," she continued. "We need to get to the palace. I believe that's where Gaster and the king are going to interview you."

We hurried off. The palace grew steadily larger as we approached, towering over us even further. The gate was opened and the captain stepped forward. A tall, heavy monster stepped into the courtyard and the captain bowed before him. I gasped, suddenly realizing I was standing before King Asgore himself. I immediately dipped my head in a bow. As I did so, I glimpsed a figure of… something behind the goat king. It was tall, thin, and strikingly dark with a white face. Could it be…? I wondered. Still bowing, I glance up further, but by the time I got a direct look, the figure was gone.

A deep chuckle met my earholes. "You can stand up. No need to be so formal," said a kindly voice. It was the king. "Welcome, you two. Sasha, who is this man?"

Captain Sasha stood up and I followed her example. "This is Fidel Amin," she stated. "He's the one you scheduled to interview today."

The king's face brightened. "Wonderful!" he exclaimed before turning to me. My naturally wide eyes grew even larger. The king was addressing me? "Mr. Amin," said Asgore with a bright smile. "Come on in. I'm so glad you've arrived. I'm sure Mr. Gaster is eager to meet you."