Ralsei and Kris first meet when Kris and Susie arrive in the Kingdom of Darkness. Ralsei, hidden under a hood, tells the Prophecy of the Delta Rune, after which he reveals more of his appearance. While Susie doesn't believe the prophecy and leaves, Kris stays with Ralsei. Ralsei joins Kris and gives them a tutorial on how to encounter enemies, encouraging pacifism.
Kris and Ralsei continue their journey together, and are not separated from each other for a long time. Eventually, they are joined by Susie, but she later decides to join Lancer as their enemy. Eventually, Ralsei and Kris get both Lancer and Susie on their team (although Lancer keeps enough distance). Lancer later sends the three to jail (this was due to him wanting to avoid having them face his father) and while Susie is in her own jail cell, Ralsei and Kris are in the same cell. After asking Kris about how they think Susie is doing, Ralsei asks Kris to close their eyes and think about how she's doing. The perspective of the player then is set to see how Susie is doing, and in this meantime, Ralsei has a mysterious conversation with Kris that we don't get to see what it is about.
After Susie frees them and now has actually changed ways for the better, the trio joins up again and travel through Card Castle and face the King together.
Kris and Ralsei separate after the King is defeated. Before Kris and Susie leave, Ralsei shows his true face and hopes he can see the two again.
If Kris stands close to Ralsei for a long period of time (face close), Ralsei starts blushing.
When discovering a White Ribbon in a chest while in the Field of Hopes and Dreams, Ralsei tells Kris to equip it since it's armor. If Kris instead equips it on Ralsei, he asks while blushing: "Well? Does it look pretty...?"
While fighting the training dummy before entering the Field of Hopes and Dreams, Kris' ACT menu has the option to hug Ralsei, which Ralsei appreciates and blushes from.
Kris and Susie both return to the Dark World where Ralsei is waiting for them both. Ralsei surprises them with rooms in his castle. Kris and Susie shortly return to the light world where they have to do a school project together, which results in them going to the library, discovering another dark world in the library's computer lab, and Ralsei returns there.
On the journey, they discover two branching paths. Ralsei asks Kris who they will go with, but no matter the response, Susie insists that he and Ralsei go together on one path, leaving Kris to go on the other path by themself, because road cones block the path that Ralsei and Susie take. Kris eventually meets Noelle and recruits her.
While in the Queen's Mansion, Susie and Berdly both go on a separate way to save Noelle (who had to surrender herself to Queen), leaving Kris and Ralsei by themselves again.
On their lonesome, they come across a giant lake of (battery) acid, which in the game files is called "Tunnel of love". Kris pulls a lever that summons a swan boat. They both ride it until they reach their stop. While on the ride, Ralsei will tell Kris about their first encounters, saying that he was nervous about first impressions and that he even hid his face. He's never had a friend before. He then says that it's nice that Susie is Susie, and that Kris is Kris. They then have a little battle with Rouxls Kaard. After the battle, they find a camera in a little land on the lake and can take a picture together there.
Kris and Ralsei eventually join up with Susie again and face Queen (two times). After some things happen, Ralsei eventually explains the Roaring to everyone and manages to (accidently even) convice Queen that her plan would doom the whole world, and then she decided to stop with all of that. Kris and Susie then sealed the fountain. They then could return to Castle Town and hangout with Ralsei again; he then tells Kris that they can SAVE and take a little rest from everything that happened.
If Kris stands close to Ralsei for a long period of time (face close), Ralsei starts blushing and tilts his head down slightly. There's a possibility that certain areas will somehow prevent this.
Before leaving the dark world for the first time, the training dummy is still in the same location. If it's interacted with, Kris can hug the dummy since no one's looking. If they do and then interact with Ralsei, he will say "Umm, sorry! Just thinking... Perhaps we don't need that dummy anymore! (...maybe you could just use the real thing?)". Making it seem like he wants Kris to hug him.
When Noelle is hiding from Queen in a disguise (in a carnival-related location) and gives Queen a prize for winning a game but shortly gives the prize to Kris after saying she doesn't want it, Susie and Ralsei suddenly show up. Ralsei asks if the prize is a gift for someone, and Kris is given the choice of giving it to either Susie, Ralsei, Noelle or Berdly. If Kris chooses Ralsei, he will have a huge blush on his face and say that he's never gotten a gift before. Ralsei is so happy that he doesn't know what to say. He wants to win something for Kris too.
When Susie and Berdly leave Kris and Ralsei on their own while in Queen's Mansion, Berdly refers to Ralsei as a "lackey" (which means someone who runs errands for another, or a servile follower). Ralsei asks Kris if they think of him as a lackey. If Kris says "Of course", Ralsei will say that he's happy to hear it. If Kris says "Of course not", Ralsei will be surprised and wonder if Kris thinks of him as more than a lackey.
While on the swan boat ride, Ralsei will tell Kris that it's nice spending time alone together like this. If Kris says that they feel the same way, Ralsei will have a huge blush on his face and will say that he's happy to hear it.
While on the swan boat ride when Ralsei is talking about Susie being Susie, and Kris being Kris, Kris has the option to say "It's nice that Ralsei is Ralsei". If they say that, Ralsei will blush and then say that no one has ever said that to him before, and hearing it come from Kris means a lot to him. If Kris instead doesn't say anything, Ralsei will say while laughing that it's Kris-like.
Shortly before the swan boat ride ends, a camera is on the sidelines. Ralsei asks Kris if they should pose, and the choices: "Do not pose", "Peace sign", "Rude gesture", and "Hug Ralsei" are shown. If Kris hugs Ralsei (which would be the obvious choice), Ralsei will act surprised and blush while the camera snaps. He asks if the camera really took a picture of that.
If the secret boss: "Spamton NEO" is encountered during a pacifist route and is then defeated, Susie asks Kris while leaving the area if they're okay and points out that they even have goosebumps. If Kris says "Yes", Susie won't believe them since they said it strained. She will then ask Ralsei if he thinks Kris is okay. Ralsei points out that they're a bit shocked but doesn't want them to worry, and not push them. Ralsei comforts Kris by saying he'll make cake for them with whichever flavor they want. Ralsei even offers to share his scarf with Kris if they're cold. If Kris says "No", Ralsei walks beside Kris and expresses a lot of worry and concern over them. He mentions that Kris is even yelling. Ralsei comforts Kris by telling them to calm down, take deep breaths, think about something nice, and even stay right next to them. If Kris hugged Ralsei during the swan boat ride before encountering Spamton NEO, Ralsei would hug Kris and an extra dialouge will be said. Susie is glad that Kris didn't die and wants Kris to warn them next time they do something stupid (referring to how Kris wanted to go alone).
- Susie – “This thing's like... Ugh, hey, why did you draw something, like, ...it looks like you guys wanna kiss?”
- Ralsei – “It's OK to express yourself, Kris.”
- — Chapter 1: The Beginning
Like other Deltarune exclusive ships, it does not have massive popularity, and has notably less fanart than Kris or Ralsei alone or Kris, Ralsei and Susie as a team. It is still one of the most popular Deltarune ships.
On AO3, it is the third most written romantic ship and fourth most written overall ship for the Deltarune fandom. It is the most popular romantic ship for both characters involved, as well as the most popular ship for Ralsei and second most popular for Kris (behind the non-romantic ship between Kris and Susie).
- r/ToothpasteBoys community on Reddit