5 years later...

"Happy Birthday, [Y/N]!", exclaimed Toriel and Asgore as you walked out of your room. Previously, they had invited you to stay over at their place for a while, even though you had your own. You wondered why they wanted you there so desperately but guess it makes sense now.

You were rubbing your eyes and yawned. "Is it already that time again? It is so hard to keep track of those things down here...", you mumbled and the smell of a sweet [favorite flavor]ed pie hit your nose. You instantly became more awake and trotted to the table, sitting down between Toriel and Asgore. You quietly sat down and Toriel lit up the candles so you could blow them out.

"You are turning 25 and we should celebrate that. So, wish for something and blow out your candles, child.", she said and you giggled.

"Shouldn't me turning 25 be reason enough to not call me child, Tori?" She shrugged and smiled at you: "I suppose, but I cannot quite let go of it yet."
"That's alright...even though, I don't feel or look any older than 22 still."

You took a quick glance at your reflection in the mirror across the room. It was true. You had changed overtime and you turned into a beautiful and intelligent woman, but since you turned 22, nothing about you ever really changed again.

Asgore snapped you out of your thoughts and laughed wholeheartedly: "Maybe she just got the best of magic properties and that makes her look younger than she is. Hence, why Tori still calls her a child." You pouted and crossed your arms in front of your chest, staring at the candle that was flickering in front of you. For a moment, you saw a glimpse of the battlefield and your heart skipped a painful beat. But that moment faded quickly, and you were still sitting on your chair with Toriel and Asgore next to you.

The door flung open with a loud crash and a rushed Gaster stumbled into the room. Some of his writings fluttered all across the room and his glasses weren't sitting correctly on his face. He adjusted his glasses in a hurry and breathed heavily.

'I came as quickly as I could when I received your message, your majesty.' His scared expression quickly turned into one of confusion as his eye scanned the room you were in. It landed on you and you blinked a couple of times to fully grasp what was happening.

You realized that you never asked him about how he broke his eye but you figured that you shouldn't push it too much and let him decide when to tell that story. If he ever wanted to.

Gaster adjusted his posture and pulled on his sleeves as an attempt to straighten his coat. 'Your majesty, I thought this is an emergency. It doesn't quite look like...' He scanned you up and down. Only now you realized that you were just wearing your night gown and you started blushing, trying to make yourself as small as possible on your chair. '...an emergency.', he finished his sentence.

Asgore smiled at him and folded his hands in front of him on the table: "Why, Gaster, of course, it is an emergency. It is [Y/N]'s 25th birthday. And there would have been no other way to get you out here, being buried in work and research all the time."

Regret flushed over his face and he ran his boney hand over his skull: 'I forgot again, didn't I? I am so sorry...'
You just smiled and laughed a little. "It's alright, Gaster, just please come join us, will you?", you asked him and pointed at the seat across from you. Hesitantly, he put down his belongings and walked up to the table to take a seat.

"Oh my..", gasped Toriel. "The candle went out. Shall I light it back up for you again, dear?" She used her magic to ignite a small flame in the air but you gently grabbed her arm, causing her to extinguish the flame almost immediately again.

"There is no need.", you said and smiled at them, then looked at Gaster: "My wishes have just been fulfilled."
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The morning went rather well, even though your friend literally saw you in just your nightgown. After the cake, you got dressed quickly and joined Gaster on his journeys to make Home a more livable space. Some monsters had complaints and ideas and Gaster was gladly coming back to them to try and turn their ideas into reality or solve their problems.

Asgore was the king, making the decisions and trying to use his wisdom to lead his fellow monsters and Gaster had a brilliant mind, who helped as good as he can to build the perfect Home.

You were sitting on a rock, kicking your feet as you waited for Gaster to finish his conversation. Sometimes you were helping, translating between both monsters since not everyone learned Gaster's signs. Usually, the conversations were held by writing and passing papers between each other which takes quite a while, so Gaster was really thankful to have you. He slowly walked up to you and you jumped off the rock, landing on your feet swiftly.

All the sparring with Asgore when you were younger helped you gain very good control over your body movements and you were also excellent at wielding different weaponries.

"Gaster..." He looked at you and raised his boney brow. "Do you think there is something weird about me? Or wrong with me?", you asked worriedly and kicked a little stone away, that was laying on the ground.

'Wrong with you..?'

"..ugh, I don't know. Don't you think I look a little too young to be 25?" You turned to him fully so he could get a good look at you. He was the only one, who could or would have a glimpse of an idea of what is going on with you. Gaster raised his hand and rested his chin between his fingers, looking at you fully concentrated.

'Honestly, you still look the same to me.'

You threw your hands up in the air: "But that exactly is the problem! Shouldn't I like somewhat look different by now? I mean, yes you are older than me and being immortal as a boss monster is pretty normal. You can literally walk around and look the same for centuries, now that you're grown-up...but it shouldn't be for me, right?"

'I guess you do have a point there..but right now I do not notice anything too out of the ordinary.'

"But-", he interrupted you by putting a hand on your shoulder and smirked at you a little: 'Trust your elders, okay?'

You squinted your eyes at him and puffed up your cheeks, playfully shoving him away from you: "Oh come on, you are not that much older than me!"

'Still older', he gave you a smut smile and grabbed his things to move on. "Oh, shooo...it barely matters."

'Yes, it does. Since I am older than you, I gotta make sure to look out for you so you don't have such an existential crisis like you just had. You're just fine, okay?'

You nodded and smiled at him, walking with you to the next monster.
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The day passed rather quickly and you found yourself walking to the last monster that Gaster wanted to talk to for the day. "Finally, the last one.", you groaned and stretched your back. 'Yes, indeed.' 

As you both passed around the corner, you saw a table set up with candles and different kinds of food. You stood still and suspiciously looked around. "Um...Gaster?" 

You turned to him and he signed 'Well, I wanted to make up for forgetting your birthday again..' He walked up to the table and pulled back a chair, signalizing you to come and sit. You were a little taken back by this gesture but you accepted anyway and sat down. As he made sure, you sat comfortably, he walked around the table and sat down himself. "How did you-" 'Most of those meetings today were dedicated to exactly this moment. It's more or less an emergency birthday gift.', he explained and picked up the fork and knife to start eating. You just nodded and started to dive in as well. It was awfully silent and the clanking of cutlery was wrecking with your nerves. "So um how...can you, you know, eat?"

'Magic.', he signed. You raised a brow and stopped eating. "That's all? No further explanation?"
Gaster put down his cutlery as well and dabbed his mouth with a napkin: 'That's the only explanation I can give you right now, but if I ever have the ability to look deeper into this topic, I let you know first of what I discovered.'

"Sounds good to me." Gaster nodded and sat up properly again.

'I am sorry, I am not really good at such things..', he apologized and got up. Without another word, he left.

You sat there, dumbfounded. Did he just dump you? On your birthday? What? Fast footsteps approached you quickly again and he returned to you, holding something in his hand. It was a small present, wrapped up in fabric.

'This is for you. I have been working on it quite a while ago but I never had the time or reason to give it to you...but now I can't get around it anymore.'
His eye flickered in a pink color and he looked away, nervously scratching the back of his neck. He placed the small item in your hands and closed them for you gently. 'Please...open it when you are back home, okay?'
"Okay, I will."

'Shall I bring you home then?'

"It would be a pleasure.'
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As things grew quiet and the lights dimmed all around Home, you laid in your bed, looking at your small present you had gotten. You took a short breath, then gently unwrapped it.

It revealed a small box, which held a single [favorite flower] in it. As you opened the box and gently touched the soft petals, the flower started emitting a few sparks that matched the color of your soul.

He must have asked Asgore for one of his first saplings and somehow modified it with magic to create such an effect. Fully in awe, you stared at the flower and enjoyed its gentle [soul color] colored glow. This flower would bloom forever, as long as your soul was still intact, and match its rhythmic glow with it.

A single tear slipped down your cheek. For others, it was just a plant with special magic but you knew what Gaster secretly tried to tell you with this.

You are still alive. You are still here. You made it through everything and bloomed so wonderfully, in the darkest of times. You were this flower, making life for many so much sweeter and beautiful with your kind and gentle nature. It was the greatest gift anyone could have ever given to you and you would treasure it for the rest of your life.

As you were about to set down the box, a small note slipped out and you picked it up.

I would really like to explain to you the different kinds of processes I went through to achieve this result.
But to keep it short, this flower made me think of you and now it's a part of you.
Hope you like it.
-Gaster

You smiled and put everything away, laying down in bed and closed your eyes.

Life surely wasn't easy but you were glad that you were able to make the best out of everything. You were thankful for the monsters around you who you could call friends and for everything you achieved so far.

Even though you were trapped in the underground.

Things hurt.

Knowing that you could never see your parents again or never had the chance to say goodbye to them properly. It hurt to have literally taken everything from you but you still made it somehow.
Everyone's kindness and determination kept you alive and going.

Life wasn't bad.
You are happy.