Kris initially appears with messy brown hair and an olive skin tone. They wear a long-sleeved green shirt with a single horizontal yellow stripe, and nondescript pants and shoes. One of Kris's distinct features is that the upper half of their face is overshadowed, which blocks visibility of their eyes.
When Kris and Susie fall into the mysterious Dark World, Kris's sprite changes. They are dressed in silver armor over a blue bodysuit, and wear a short, torn pink and blue cape. Their skin and hair turn blue, which is most likely to reflect the lighting (or lack thereof) underground, in keeping with the visual and story themes of light and dark.
Kris's overworld sprite has almost the same color palette as an unused human sprite inside the files of Undertale, the only difference being Kris not wearing blue pants. Their clothes in Hometown are very similar in color palette to Chara's, their cape in the Dark World instead shares its coloring with Frisk's shirt.
Kris shares several properties with the human children from Undertale, including a similar name to Frisk, and similar clothing to Chara. Like Chara, Kris enjoys chocolate, and takes chocolate kisses from Toriel's room without permission. They also enjoy drinking hot chocolate at QC's Diner.
The other characters have mixed opinions of Kris. Some call them a "creepy kid," others see them as nice. In the Dark World, the others see Kris as a "leader." Ralsei and, eventually, Susie follow their commands in battle and follow them around the overworld. Susie and King refer to them as a "quiet person." Their side of their shared bedroom is strikingly bare, including the shelves that the books now in Toriel's classroom must have previously occupied. They have a history of not waking up on time. When they were younger, Asriel sometimes carried them to school.
According to many of their neighbors, Kris has always been mischievous, pulling dark pranks such as covering themselves in ketchup and claiming it was blood. For example, Kris has the option to keep flushing the toilet before or after going to school, with Toriel replying: "You did not put a bath bomb in the toilet again, did you?" However, her view of the pranks seems to be as a minor annoyance, or even endearing, considering the fact Toriel sounded like she was at most a bit annoyed with the behavior. Townsfolk also appear to be surprised to find Kris voluntarily engaging them in conversation. If enough characters are talked to before returning home, several characters remark that Kris looks sick, strange, or pale.
Kris is first encountered when they are awoken by Toriel for school. At this point it is possible to go to School, or skip it by returning to bed. (Only after completing Chapter 1 once. Skipping school immediately dumps Kris into the Dark World.) If followed outside, Toriel drives Kris to school, leading to a short tour of Hometown.
Kris, being late to class, is told by Professor Alphys to pick a group partner. When Noelle Holiday is asked, she checks with Alphys about letting Kris join her group with Berdly, though Susie barges into the classroom, interrupting the proceedings. Kris then gets paired up with Susie. Afterward, Professor Alphys realizes there is no chalk for her to teach class with and sends Susie to go get some from the supply closet. She then asks Kris to go with her.
In the hallway, Kris witnesses Susie eating a piece of chalk. Once Susie realizes Kris is there, she approaches them menacingly, slams them against a locker, and threatens to eat their face. She then drops Kris on the ground, stating that Kris has a good mother and "It'd be a shame to make her bury her child."
Once at the supply closet, Susie opens the door, only to be perturbed by the eerie darkness emanating from the closet itself. When Kris and Susie enter the closet, they wander deeper and deeper looking for a light switch, only to find none, nor any walls for that matter. As they approach the door to leave, it slams shut. Papers beneath their feet begin to quiver and shake, and then fall into a void, with Kris and Susie following suit.
Kris awakens in a strange, unknown world, with their street clothes having been exchanged for armor and a cloak, and their skin now a bluish hue. After some exploration and sightings of a shadowy figure, Susie is found hiding in a pile of dust.
After a bit more walking, Kris and Susie are attacked by the mysterious figure, who is later revealed to be Lancer. After escaping, they come across Castle Town and encounter Ralsei. Lancer then interrupts Ralsei, accosts Kris and Susie and fights them for the first time. After the fight, Susie leaves on her own in an attempt to find her way out of the Dark World, leaving Kris and Ralsei on their own. Eventually, Kris and Ralsei catch up with Susie, who begrudgingly rejoins the party.
After numerous encounters with Lancer and getting mad at Ralsei for telling her not to fight, Susie decides to join Lancer instead for a while. This culminates in an encounter between Kris and Ralsei versus Susie and Lancer. At the conclusion of the fight, Susie once again rejoins the party, and Lancer tags along.
Eventually, Lancer grows uncomfortable with the situation and runs off towards Card Castle. Kris and the party attempt to follow him, but some of the King's soldiers capture them.
Ralsei and Kris wake up in a prison cell together, but the two quickly realize that Susie is being kept in an adjacent cell. Kris manages to guide Susie through a puzzle, unlocking her cell and allowing her to escape. After a confrontation with Lancer, Susie is able to release Kris and Ralsei from prison.
After making their way up Card Castle, Kris and the party face off against the King. After the fight, King deceives the party into believing he is willing to redeem himself, resulting in the party being cornered. Kris jumps in front of Susie to protect her, but is knocked back by another blow. King approaches Kris and, after taunting them, lifts them into the air, ready to kill them. Regardless of how the King was initially defeated, either Lancer and the King's subjects rescue the party, or Susie musters the strength to cast Pacify on the King, putting him to sleep. Which outcome occurs is based on whether or not the party harmed any of the denizens of the Dark World prior to facing the King (except for Jevil, Lancer himself and the first C. Round).
After saying goodbye to Ralsei, Kris is able to seal the Dark Fountain and return home, along with Susie. Kris can then choose to explore Hometown and speak to the inhabitants. Once Kris returns home and goes to bed, the adventure is over.
At some point in the middle of the night, Kris tosses and turns in bed, only to suddenly leap from their covers and jerkily make their way into the center of their room. As they stand on the carpet (emblazoned with the Delta Rune), Kris slowly raises their arm before violently tearing out their SOUL from their body and forcefully tossing it into a cage in the corner of the room. The SOUL can be moved in the cage, indicating that the player controls the SOUL, not Kris. Kris brandishes a knife that glistens in the light from the window before turning their head and smiling menacingly with their eye flashing red, similarly to the ending of a "soulless" Pacifist Route in Undertale. The game then cuts to black.
As a human, Kris cannot cast spells. Instead of casting spells, Kris uses the ACT command in different ways depending on the enemy being faced. ACTs usually cost 0 TP to perform, although there are a few specific instances where an ACT cannot be executed unless the party has a sufficient amount of TP. In the fight with King, Kris can act with Susie and Ralsei to create improved versions of their spells. "Do all sorts of things. It isn't magic."
The following are ACTs that cost TP and only Kris's turn:
Requires 25% TP. This ACT is only available during the fight against King, replacing Kris's Talk ACT after attempting to talk to the King. Kris encourages the party, raising all of their DEFENSE stats for one turn.
Requires 20% TP. This ACT is only available during the fight against Jevil. Causes Kris to perform a pirouette gesture, tiring the boss and causes a specific effect depending on what turn it is. The effects are as follows:
- Turn 1: Nothing happens
- Turn 2: Lowers the bonus boss's defense
- Turn 3: The number of invincibility frames decreases this turn
- Turn 4: Party DEFENSE up
- Turn 5: Nothing happens
- Turn 6: Heals a random party member
- Turn 7: Shuffles all of the party members' HP bars
- Turn 8: The boss's next attack is stronger
- Turn 9: ~30 HP heal to all party members
- Asriel and Kris made a sculpture of an angel for youth group, except they spent the whole time making large wings for it.
- Kris's pranks have included hiding under Noelle's bed when they knew she was afraid of humans under the bed and telling her that Ice-E was real and ate children, after which another child, Dess, hit Kris with a wiffle bat until they "stopped lying."
- Kris plays the piano, but they never sang in the local church choir with Asriel.
- If they attempt to play the piano in the hospital, however, they just slam on the keys, and the monster at the front desk comments that they usually play better.
- Kris is exclusively referred to using singular they pronouns, similarly to Frisk and Chara from Undertale.
- During the final moments of Chapter 1, when Kris throws their human SOUL into the birdcage, the player can still control the disembodied SOUL, though all it can do is slowly move around the inside of the cage.
- Kris, like their party members, has several different titles in the party menu.
- The name "Kris" holds some potential meanings:
- A kris is a type of ritualistic dagger, a possible nod to the knife Kris wields at the end of Chapter 1.
- The etymology "Of Christ," as a nod to the fact that Kris's family is or was very religious.
- A combination of Chara and Frisk's names (Chris being the Ch from Chara and the rest from Frisk) with the letter K substituting Ch from Chris.
- When defending in a fight, Kris turns their sword into a shield.
- Interestingly, while Kris has 90 HP when in the Dark World, in the overworld they have 20 HP, the same amount as Frisk at LV 1.
- Original DELTARUNE concept art of the main characters from 2014 or 2015??? The file was just called "THE FUN GANG" - Toby Fox (@tobyfox) on Twitter, November 16, 2018.
- Huh...? Kris...? Did you say something back there? [...] (... I can't hear them anymore...) - Susie, when following Kris's instructions for saving them and Ralsei from prison