Collei is a character who has only appeared in the manga. It is not certain if they will appear in-game.
Collei is at first presented in the manga to be slightly cold, and not understanding very well how happy-go-lucky Amber can be. The more she experiences Mondstadt, however, the more she gets excited and happier, giving her resolve to seal her Archon residue no matter the consequences.
Collei is by estimation 10 centimeters shorter than Amber, and her appearance details wavy, short, light green hair that goes to her neck with purple eyes that almost touch magenta.
In her first appearance in the manga, she is wearing bandages covering her face to her arm, and she is wearing grey rags and saggy pants, with a grey trapper hat constructed out of bandages.
However, as the guest from Sumeru Academia seals and puts her archon residue to a dormant state, she is free from the bandages, and, as seen in Chapter 16, she is wearing a black shirt which layered over by a beige messenger's sack, and wearing a black cape over both. She wears a lime green and yellow bandanna like belt with black shorts, with boots and socks almost to her knee. And, as her "trademark style", she is wearing a proper black trapper hat with white fluff inside.
This section contains spoilers. Proceed with caution.
When Collei was first born, she unfortunately was not so lucky and got the plague. Her worried mother desperately begged the servants of the 8 harbringers of the Fatui to save her, and without hesitation, the servant took Collei away to supposedly save her, however, instead of saving her, they performed experiments on Collei and put Archon Residue inside of her.
It soon became apparent to her parents that the Fatui didn't intend to return Collei to her family, and with fear that she wasn't healed, they demanded the servant for their daughter's whereabouts and to see her. However, the servant pretended that he didn't know what they were talking about, and coldly told the guards to "get rid of them", supposedly killing her parents.
The experiments performed on Collei were not kind. Due to the experiments, Collei developed a fear for enclosed spaces, and due to nobody ever helping her when she cried for help, Collei grew pessimistic on the idea of ever asking others for help or having friends, developing a strong hatred to the gods and failing to see things as beautiful. And, unfortunately, she was made unaware that her parents did return and begged to see their daughter, and was led to think that her parents had abandoned her, only making her hate on relying on others stronger.
It is unknown if the Fatui let Collei go or if Collei escaped herself, however, she was not treated kindly by the people of Sneznhaya. She was often abused by passing pedestrains, being called names, thrown rocks, and pushed around. This only led to fuel her hatred for the people privileged and strong desire for vengeance. In search for revenge, Collei traveled far by walking all the way to Mondstadt in the belief that Mondstadt holds the key to her vengeance.
Upon arriving to Mondstadt, she was refused in due to her carrying the plague, and in anger to Mondstadt refusing her entry, she summoned a snake composed out of dark magic and attacked a leaving carriage, which incidentally was the carriage that held two envoys sent by the Fatui. The two envoys died in that fire and 15 were wounded despite the Ordo Favonius escorting them. This caused a divergence and allowed Collei to slip into Mondstadt.
The Ordo Favonius was stricken by the failure and so both Amber and Kaeya were sent to investigate. While investigating, Amber saw Collei looking at a statue with anger, and questioned her on what she was doing out here so late. Collei was impatient and tried to convince Amber to let her be, but, unlucky she was, Amber was not easy to let go. Saying enigmatically "I'm here to look for something... But I don't think I'll find it", Amber decided to help Collei find whatever she was looking for. Despite Collei saying that she didn't need help, Amber still dragged her along.
While dragging Collei around, Amber decided to fly with Collei and see if she could see what she was looking for, and as a surprise for Collei, she didn't think that the view would be so pretty, nor had she ever dreamed of one day flying. Upon landing, Amber met Jean, the second in command of the Ordo Favonius and Lisa, the librarian of the Ordo Favonius, who invited Amber to share their intels, proposing to go to the library. At first, Amber did not want to go for she had no intel on hand, but Collei knew that what she was looking for could be in the library, convincing Amber to go and bring her along.
While Amber suddenly left to go look for an important clue and Lisa had gone to find Diluc, Collei took the scroll which described, apparently, what she needed for her revenge. Collei was caught by surprise as she couldn't read a single thing on that scroll. Just at that moment, Kaeya found Collei and started to question her on why she had the scroll, and what she was doing here, until Amber came back from her small adventure and stopped Kaeya from questioning any further. Lisa had also returned, and with no choice, Collei had to give back the scroll with a cover-up saying "you forgot this" and, Collei is only further disappointed to learn that Lisa cannot read the scroll either.
With their new intel gleaned from many sources, both Collei and Amber went to look for more clues and suspicious items. Incidentally, that was also the day of Ludi Harpastum, the yearly festival of 15 games for the children to enjoy. Amber decided to let Collei see the wonders of Mondstadt, and instead of searching for suspicious items, Amber brought Collei to the festival. Although, Amber herself did not realize everything she was doing for Collei was changing a heart once full of hatred.
In the circus, Collei was chosen as a volunteer, and was enclosed in a wooden box, which caused Collei's memories to resurface and lead her to the brink of a breakdown. As Amber opened the box after being asked to, Collei realized that Mondstadt is not a dangerous place; it is a place where you are free to be happy, to smile, to cry, as she starts to realize that she would like to live a life like that.
Unfortunately, Kaeya caught on to the hint that Collei might've been the culprit all along and tells Amber that they have found another one of Fatui's little birds, sending her off and allowing Kaeya to apprehend Collei. Although Collei was resisting using her Archon Residue, her Archon Residue attempted to gain control of her vessel. Luckily, Amber found Collei just in time as her Archon Residue was attempting to choke Kaeya, and brought Collei to a balcony where Amber herself apprehended Collei.
However, Amber was not cruel, seeing that Collei was trying to right her wrongs. Amber then told her that they had decoded the papers and could help Collei find what she needed. However, Collei no longer needed revenge and now only wanted to turn a new leaf, revealing that Lisa has also figured out that she was the culprit and sent for someone at Sumeru Academia to put her Archon Residue in a dormant state. It was also revealed that the Archon Residue is strongest at nighttime.
Next morning, Collei put her Archon Residue in a dormant state sucessfully, finally allowing her to turn a new leaf. However, just as Amber and Collei were happily celebrating, the servant found Collei, and was ready to take her away. Amber remained vigilant and refused to give Collei up, and engaged in a near death battle with the Fatui.
Watching Amber getting herself injured for Collei, she fell to another brink of despair, with the Fatui taunting her to free her Archon Residue for the power to protect her friend, which would only in truth do the opposite. Collei, for the first time, realized that she was completely helpless and felt immense guilt, asking Amber why she would want to put her life on the line for someone like herself. Amber reassured her, telling her that she will live with all the power she has.
Collei suddenly realized what she wanted was not the power for revenge. What she wanted was the power to protect those she cared about. Together with Amber, Collei gained the resolve that she would not run away again and defeated her haunting obstacle and her desire for vengeance.
After recovering, Collei visited Lisa and asked to learn how to write. She wrote a letter to Amber revealing that she would be going to Sumeru Academia to learn more vast knowledge. An apology was also included for not being able to say goodbye to Amber personally, reassuring that she was alright. Leaving Amber in peace, she thanked her friend for making Mondstadt so fun for her.
- There are hints she is claustrophobic.
- Due to the Archon Residue feeding on Collei's negative emotions, when she encounters such a negative emotion, the Archon Residue let Collei have a vision of what would happen if she had control over the Archon Residue and was filled with hate.