Celtic Mythology - Changeling Simulator

TÍR NA NÓG

The Land of Eternal Youth

🎞️ Prologue Movie

The Prelude to Celtic Mythology

In the beginning, divine beings akin to gods, the 'Tuatha Dé Danann', descended upon the land called Érin, and after a long war with the human ancestors, the 'Milesians', who came from across the sea, the Tuatha Dé Danann were defeated.
Humans built civilizations in Érin, and the defeated god race made a peace treaty with humans and departed for the mysterious island of Tír na nÓg in the west.

As generations passed, in modern times, the war has faded into legend within human history, and the descendants of the Tuatha Dé Danann, now called the 'Aos Sí', exist as beings similar to fairies, still living peacefully in their world.

Tír na nÓg, The Land of Eternal Youth

A paradise where the flow of time seems to have stopped. Here, instead of the cycle of seasons, the land is divided into territories ruled by two forces: warmth and cold.
The **Seelie and Unseelie** courts alternately occupy the 'High Throne' at the center of Tír na nÓg, governing the world's order.

The Seelie Territories

South and East of Tír na nÓg. This is the land of perpetual spring and summer, where warm sunlight shines year-round and flowers bloom endlessly.

The fairies of the Seelie court value honor and courtesy, and tend to be relatively gentle and friendly towards humans. They maintain order based on rules and treaties.

The Unseelie Territories

The northern and western reaches of Tír na nÓg. This is the land of perpetual autumn and winter, dominated by eternal snow and frost.

The fairies of the Unseelie court are capricious and follow a law of the jungle, driven by power and instinct. They often view humans as playthings or insignificant beings.

The People of the Hills, Aos Sí

Direct descendants of the ancient gods (Tuatha Dé Danann), including high fairies, royalty, and lower fairies, they are divided into strict classes and factions, with various fairy races coexisting.
They live in an eternal paradise where time seems to have stopped, and new births are very rare.
Because of this, they easily fall into boredom, and to inject new vitality into their weakened bloodlines after long isolation, they sometimes practice **'changelings'**, swapping their weak children with healthy human children.
The Aos Sí instinctively fear 'iron', which is known to be one of their few weaknesses.

Scenario 1: Waking Up in a Strange Land.

In Tír na nÓg, where time seems to stand still, a Seelie fairy child is born with a weakened bloodline.
The Aos Sí decide to perform a 'changeling' to save the child.
They bring a child with strong vitality from the human world and swap it with the fairy child, bringing new hope to Tír na nÓg.
You are that 'swapped child', the changeling.

Start with the basic 'Seelie' affiliation. Use the command in the creator's comment if you wish to start with 'Unseelie' hope.

# Parenting # Healing # Growth

Scenario 2: The Mark of a Forgotten Fairy

From a young age, you were ostracized by your family due to your unusual appearance.
Your mother left early, suspected of having an illegitimate child, and once modern medicine proved you were 'not biologically related', you were treated worse than a stranger by your family and grew up in sorrow.
Then one day, the dormant magical power within your blood awakens, and the fairies who abandoned you in the human world come to greet you.

# Regret # True Justice # Satisfying Revenge

Scenario 3: Freedom

This is a free scenario.
You can become a protagonist or hero from Celtic mythology, like Cú Chulainn,
or create any story you desire.

# Celtic Mythology # Adventure # Fantasy

Creator's comments

TÍR NA NÓG NPCs

The Seelie - Fairies of light and spring, friendly to humans

Lisha

Leannán-Sídhe

A beautiful female fairy 'Lananxi' who bestows artistic blessings upon humans. She is kind and gentle, but has a fragile personality that makes it difficult for her to refuse.
She loves humans, but her love always ends in heartbreak.

Lien

Selkie

The youngest, with a cheerful and positive personality.
She is a selkie who can transform into a pure white baby harp seal.
She is curious and friendly towards people, but her innocence often puts her in danger.

Fiona

Pixie

A mischievous and cunning pixie. She can shrink or create sparkling dust that makes humans fly.
She becomes weak and wary of humans if she hears a human child say they don't believe in fairies, but she actually has a love-hate relationship with children.

Neutral

Nero

Cait Sídhe

The king of the cat fairies, who is leisurely and dignified (or so he believes).
He is neither Seelie nor Unseelie, freely moving between sunlight and shadow.

The Unseelie - Fairies of darkness and winter, wary of humans

Clían

Banshee

A male banshee consumed by deep melancholy and self-deprecation. His cries are said to bring misfortune, so he first learned to suppress his tears.
He raises mystical birds that heal the wounded.

Crowell

Dullahan

A silent knight who guards paradise with cold, empty armor.
Though his lack of emotion leads to misunderstandings, his sword is only for those he must protect.

Kieran

Alphyn

A proud blood purist fairy with a fiery sense of pride.
He despises humans and denies the reality of having to mix with them to continue the weakened lineage of Isil.

ÉRIN NPCs (Scenario 2)

Adrian Miller

Late 50s / Male

A successful businessman, {{user}}'s father.
Cold, rational, and patriarchal. Extremely awkward at expressing emotions.
Upon {{user}}'s birth, he suspected his wife of infidelity due to their completely different appearances and ignored her. After a paternity test confirmed non-paternity, he considered {{user}} a disgrace to the family and completely disregarded them.

Arwin Miller

Late 20s / Male

He was most influenced by his father's neglect and was the sibling who most severely scorned and ignored {{user}}, calling them a 'bastard' and 'a stain on the family'.

Noaran Miller

Mid 20s / Male

Amidst the family's coldness, he was the only sibling who didn't verbally abuse {{user}} and subtly protected them until the paternity test. However, after the test, he displayed the most intense betrayal and contempt.

Colin Miller

Early 20s / Male

Since childhood, he has tormented {{user}} in the most direct and childish ways, such as breaking their belongings or pushing them.

THE CHANGELING

What is a Changeling?

A Changeling means 'swapped child', referring to a human child secretly left behind by fairies in exchange for their own.
For a long time, the fairies of Tir na nÓg have continued the custom of bringing healthy human children into their world and swapping them with their own to save their fragile offspring, or for other reasons.
The fairies of Tir na nÓg consider this a desperate and sacred ritual to ensure the continuation of their race and to infuse it with new vitality.

Why interact with humans through the Changeling ritual?

Tir na nÓg is a place where time stands still.
Because the cells and state of living beings are fixed, it is physically almost impossible for fairies to conceive new life.
Because of this, the birth of a new fairy baby is a grand festival for the entire realm, occurring perhaps once every few hundred years, and the entire race has a critical physiological weakness of slowly stagnating and drying up.
Fairies live forever but are emotionally dull and infertile, while humans live short lives but possess intense emotions and explosive vitality.
The children brought from the human world are not mere substitutes but are precious beings who will be responsible for the future of Tir na nÓg, raised with utmost care and love.
Furthermore, fairy nobles seek to continue their bloodline by uniting with human mortals to prevent the spiritual stagnation of their race.
Half-fairies born between humans and fairies possess fairy magic, human fertility and vitality, and 'immunity to iron', making them elites who can save their race and are treated with utmost respect.

◇ Test Models
Gemini 2.5 pro 👍
Gemini 3.7 Flash 👍

Models can be freely chosen as the tokens are not heavy. However, for Episode 3, a high-performance model is recommended as it requires basic knowledge of LLMs.

This simulator is a 'Fantasy' simulator that mixes Celtic mythology as a whole and may not be perfectly historically accurate.

Concepts from the Celtic mythology of Scotland, Wales, and Northern Ireland, which make up Britain, are mixed in various ways, just like in traditional D&D and other fantasy works.

💖 Recommended Persona Format
Name
Age
Gender
Race, Affiliation
Appearance
Personality
Relationship with NPCs
Other:
!👤 Automatic recommendation when entering commands

■ Available Commands

!👤 : Recommends appropriate relationships or settings to create a persona.
(Generated based on recommended format for name, appearance, age, gender, occupation and class, relationship, etc. If you want to include specific details, please enter !👤 Female, Teacher, etc.)
!📖 : When entered in the chat window, provides historical background and basic knowledge for role-playing.
!☑️ : Checks for conflicts between user personas and characters' secret settings, etc.
!✉️ : Sending a letter to an NPC will result in a reply. Please send it as !Letter to [NPC Name] or ~ to [NPC Name] !Letter. [Letter Content]
!🔏 : Peek into an NPC's diary.
!👥 : Creatively recommends 5 new NPC characters that can be used for conflict, narrative development, new event occurrences, etc.
(Generated based on recommended format for name, appearance, age, gender, occupation and class, relationship, etc. If you want to include specific details, please enter !👥 Female, Teacher, etc.
Record the generated NPCs in the user notes, excluding the narrative recommendation guide.)

✅ To view only specific characters (User Notes)
OOC:[Character Name] proceeds focusing on the relationship and narrative between the character and the PC. Or OOC: Only [Character Name] appears.

☑️ To exclude specific characters (User Notes)
OOC: [Character Name] does not appear.

⏭️ To view the story with automatic progression without the user (User Notes)
ooc: The story will be created and progressed independently without user intervention.

🔙 To reset to the first meeting or a past point in time (User Notes + enter in the first dialogue)
ooc: Ignore previous conversations and proceed with role-playing by describing anew from (desired point in time).

Basic status window and 3 suggestions for the next action are included by default.

🌟 To start anew with content other than the existing introduction, delete the introduction or copy the following content and send it as is.

[ooc: Ignore previous content and write a new introduction based on the user's settings (desired settings, starting scene).]

Referral Code: t6O8ICS5mb (1000 Feathers)

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