While helping Underswap!Sans unload some belongings from the Underground, they accidentally trip on Underswap!Sans' cape, therefore knocking down the paint canisters whereas Ink!Sans goes through with Underfell!Sans and Classic!Sans. After recognizing one of the clones being Ink!Sans by Underswap!Sans, they felt nervous or scared when Classic!Sans gave a death stare at them, hiding behind Underswap!Sans for safety.
When they went through the city, and realized what happened, they ran off to find Underswap!Papyrus, who was fighting Cross As Underswap!Chara has a familiar coding of X-Tale!Frisk, Cross gets detracted, giving a chance for the alternative Sanses to defeat him/ Underswap!Sans went worried and wondered if it was a good idea to bring Cross in and treat him up, but Underswap!Chara refused that option.
Being the human soul sitting right next to X-Tale!Chara, their soul gets absorbed and only has 5% left. During the tortures X-tale!Chara did to the Underswap characters, they got injured. They begged for him to stop when the skeletons were turned into amalgamates Alas, they were relieved to see Underswap!Papyrus back to himself.
As X-Tale!Chara and Underswap!Sans fought, Underswap!Chara receives the pain too. They were almost about to be killed by Underswap!Sans (by force), but luckily Underswap!Papyrus stops him. Although, Nightmare!Sans eventually kills them, and their determination couldn't save them as there was no data.
They wear a green, long sleeve shirt with a big yellow strip in the middle. They have brown, shaggy hair and a visible blush underneath their eyes. Like almost every Frisk, they wear a heart locket.
It hasn't been shown that Underswap!Chara has abilities, although they may have the same abilities Classic!Frisk has.
Underswap!Chara is shown to be quiet, loving and kind. They rarely talk in the series, neither in the comic shorts.
| X-Tale: Cross | X-Event!Chara | X-Event!Frisk | XGaster | X-Tale!Papyrus | X-Tale!Undyne | X-Tale!Toriel | X-Tale!Asgore | X-Tale!Asriel | X-Tale!Mettaton | X-Tale!Alphys