Disclaimer: I don't own Touhou Project and its characters. This section will include some elements from Imperfect Metamorphosis by TakerFoxx.
Name: Rin Satsuki
Aliases: The Blob Monster. The Kirin. The Mimic Kirin. The Adaptive Kirin. Eitentai's Kirin. The doppelgänger Kirin. The Copy Kirin. The Blob Kirin
Race: Kirin
Abilities: Rin is capable of turning into a blob of mass that is hard to take down. She can shapeshift into a form that best suits the situation and problem she is facing. It also worth to note that Rin becomes more resistant to the same attacks done to her multiple times. Even before her transformation into a blob, Rin was able to adapt and her power amplified after her metamorphosis.
While learning under Eirin, Rin was able to learn how to craft medicine, and different types of elixirs that prove useful to herself and her friends.
Rin is also an expert on guns, after training with Reisen, meaning she knows the inner workings of a gun. She also has great marksmanship when wielding guns.
Originally Rin was able to dissolve anyone she comes across, absorbing their body and gaining their powers, though the victim she absorbed is still alive. However, Eirin along with her apprentice Reisen and 4 others managed to fix Rin's powers. She now no longer can absorb people, but she is able to perfectly mimic their powers and skills, after seeing it once.
Possessions: Just like Reisen, Rin possesses some guns that were given to her by the former moon rabbit.
Personality/Appearance: Rin is described as a content and calm individual, but will be enraged if anyone talks badly about Reisen or Eirin for that matter. She follows her orders faithfully from her superiors, but will sometimes question why the order is so important.
Rin looks up to Reisen and some of the rabbits, except Tewi, as her older sister figures, and love them for that.
Rin wears a white blouse with a red bow at her neck, she also has a red skirt. She has straw colored hair, with a red ribbon tied onto her head.
Backstory: Before Rin was born her two parents were both criminals of the Kirin. Her father ended up having sex with another Kirin, before a wedding ceremony with his fiancé. This ended up causing them to be marked as criminals, but they managed to get away from their pursuers. While escaping Rin's unnamed mother gives birth to her. They both sold the toddler Rin to a group of human slavers so as to travel lighter, and no one, even Rin doesn't know where they went.
While in captivity, the slavers were attacked by Eitentai's guards, after they kidnapped two infant rabbits from one of the rabbit tribes. They ended up clearing out the slaver camp, and returned all of the enslaved children to where they came from, except for Rin. Originally Rin was going to be sent back to where she came from by Eirin, but was overruled by Kaguya. After this event Rin, basically lived in Eitentai as her new home.
In Rin's younger years at Eitentai, she helped around with running errands, cleaning, and other things. When she got older she wanted to aspire to be just like Eirin, but had to pass a self-defense class in order to do so. While in the class Rin sucked, she couldn't come up with the most basic of spell cards, and she was terrible at close quarters combat. However, due to her determination Rin didn't give up, and asked Reisen to help her get good, who gladly accepted.
After a few weeks of training with Reisen, Rin found out that she has adaptation powers. She then decided to use her newly discovered powers to help her do better with physical and magical points during the self defense class. This led to Rin passing the class, and becoming Eirin's second apprentice besides Reisen. Being a hardworking individual Rin, then asked Eirin if she can help her improve her powers to become more powerful. Eirin agreed, and she along with Rin tried finding ways to improve the Kirin's adaptive abilities, to no avail.
Eirin decided to go get some help, so she got Patchouli Knowledge, Sakuya Izayoi, Yumemi Okazaki, and Chiyuri Kitashirakawa to help her. They ended up creating a new kind of similar just like the Hourai Elixir, which they then injected into Rin. After this Rin was able to adapt to new energies, too well, and ended up melting into a mass of blob.
After Rin's metamorphosis into a blob that is capable of absorbing people to gain their power. Eirin sought out a way to find out a cure for the Kirin turned blob along with her apprentice Reisen, Yumemi, Patchouli, Sakuya, and Chiyuri. A few weeks later, they found out the cure to Rin's unfortunate predicament.
To perform the cure, they convinced Kaguya to help them by using her manipulation of eternity on Rin to stabilize the Kirin's condition. Then they will give the blob Kirin remnants of the Hourai Elixir that Mokou drank, after she it stole from Eirin.
After this process, Rin was successfully brought back to her former self….ish. Although the distribution of the cure was successful, the Hourai Elixir given to Rin was half of what it originally was, and this meant she still (somewhat) has some of her powers, when she was a blob. Other than that she is able to still live a normal life.
Fast forward around 19 years later, Rin has gotten a lot better at fist to fist combat, and actually knows how to form spell cards now. She also learned how to better use her adaptation powers to her advantage. Rin also figured out how to incorporate her blob powers to mimic moves and abilities of her opponent while fighting them.
During the Eternal Night Incident, she along with Reisen tried to defend Eitentai from the incident resolving teams, but were overpowered by Reimu, Yukari, Sakuya, and Remilia.
After that incident, Rin wanted to learn more about Gensokyo, after being cooped up in Eitentai for most of her life. During her trip around Gensokyo she ends up meeting and befriending Team Nineball.
Relationships:
Kaguya Houraisan: Kaguya was the one who allowed Rin to stay at Eitentai, after she was rescued from the slavers. The reason behind this action was, because she felt sympathy toward the Kirin. The former lunarian princess played a major role in Rin's curing by using her manipulation over eternity to stabilize the Kirin's condition. Kaguya also introduced Rin to the amazing world of video games, after the Kirin saw her playing Mario Kart.
Eirin Yagokoro: The Lunarian doctor is Rin's master/idol figure, she the Kirin wanted to be just like Eirin. After Rin managed to pass the self defense exam of Eitentai, Eirin took Rin as her second apprentice beside Reisen. Eirin also started to warm up toward her new apprentice, and actually become somewhat of a mother figure to the Kirin. The doctor played a major role in Rin's metamorphosis, and curing. Rin also follows Eirin orders, when the doctor gives them to her. The doctor also helped Rin in learning how to make medicine.
Reisen Udogein Inaba: Reisen helped Rin with training on how to get good when she was younger. Rin considers Reisen her older sister, after she took care of the Kirin during her younger years. Reisen also helped Eirin in searching for a cure for Rin after her metamorphosis. The former lunarian rabbit also trained Rin to get good, with fist-to-fist combat, and spell cards. She also taught the Kirin to be able to use guns properly.
Tewi Inaba: Rin just like Reisen is unfortunate enough to be the victim of many pranks Tewi does to her. Though Rin has gotten better at countering the pranks, the earth rabbit still pranks the Kirin to her ire.
Yumemi and Chiyuri: The two professors were the ones who aided Eirin in creating the elixir that was responsible for Rin's metamorphosis. They also played a major role in curing Rin. Afterwards, Rin will sometimes visited the two of them to help them test out new gadgets, and help contribute to making new medicine to use in Gensokyo.
Patchouli Knowledge : Patchouli is Rin's teacher in how to use her magical capabilities. The Voile librarian along with Sakuya were the ones who assisted in Rin's metamorphosis, and eventual curing.
Sakuya Izayoi: Sakuya along with Patchouli were involved in Rin's metamorphosis and curing. The head maid used her time powers to speed up Rin's power development to make things faster, before her metamorphosis. While finding a cure Sakuya placed a time barrier on Rin to make sure she doesn't absorb anyone who touches the Kirin. After Rin was cured, Sakuya resumes her 'normal' life as her mistress's maid. Rin and Sakuya are acquaintances with each other after this event.
Team Nineball: While venturing throughout Gensokyo, Rin meets the team of weaker youkai while she was at Misty Lake. She ends up befriending the group, after she joined them in one of their games. The Kirin considers team nineball to be her very first friends.
Theme Songs:
【東方 Original】 花鳥風月は彷徨い歩く ～ Phantasia of Fantasy 「sm17365699」
FM Rin's Theme: Isolated Blossom of Prunus Serrulata ~ Descending Pink