Frans

Frans is the non-binary ship between Frisk and Sans from the Undertale fandom.

Canon
Frisk first meets Sans in Snowdin Forest where he pranks them with a whoopee cushion. He then laughs and and explains about himself and his brother. It results in a funny scene with his said brother, in which the Snowdin arc of the game begins. Throughout the arc, Sans shows up in random places and along with his brother.

His next notable appearance with Frisk is when he invites them to Grillby's for a chat. Sans asks about a talking flower (in which the player can make Frisk say yes or no) that hints towards Flowey, though Sans covers it up with the idea of an echo flower. During this scene, Sans "accidentally" ruins Frisk's fries or burger by dumping the entire ketchup bottle on it. Sans says Frisk can have his instead because he wasn't going to eat it anyway.

Later in the game during the Hotland arc, Sans is seen running a hotdog stand which will lead to a funny scene with Frisk. If the player's inventory is full, Sans will start to stack hotdogs on top of Frisk's head until he is unable to reach anymore.

Near the end of the Hotland arc at the MTT Hotel, Sans invites Frisk to dinner within the hotel. What occurs is that Sans tells a story about a lady beyond a door in Snowdin he used to tell knock-knock jokes with. The lady had apparently told him to keep watch and protect a human if they ever go through the same door, which he complied. He said to Frisk that if this hadn't happened, "You would be dead where you stand." He brushes it off as a joke afterward, but it's unknown if he was joking or not. A popular line of his to Frisk during this scene is "I'm rootin' for ya, kid."

The last Frisk sees of Sans in the Neutral run is in the Judgement Corridor where Sans will judge Frisk and the player for every EXP and LV they have earned throughout the game, as it was revealed that these stats mean different things. Reactions vary depending on the stats, but the most friendly is that he claims Frisk has not obtained LV or LOVE, but love inside of themself and leaves them to decide the Underground's fate.

If the player manages to get a True Pacifist run, Sans appears near the end of the game along with all the other friends Frisk got during their adventure. Once Flowey- or Asriel- appears, Frisk saves Sans along with the others by reminding him of the interactions and the friendships they both had along with Papyrus.

At the end of the game where everyone looks off into a mountain, Sans does not interact much with Frisk but is still friends with them.

Platonic
The pairing is very popular platonically. Because of Frisk being a child, many love the relationship as a father/child or an uncle/child duo and that kind of relationship between them is illustrated in many ways. Popular AU's depicting them with this relationship is Endertale, GlitchTale, Underverse and etc. It is also popular in fan art and fan fiction.

Romantic
This ship receives a lot of backlash due to Sans being much older than Frisk, with Frisk having no known age other than what seems to be a child. To make up for this, people often ship an adult version of Frisk with Sans instead (or make an AU version of them). Frisk is often portrayed as female in Frans, but canonically, just like the first human, they have no stated gender and are solely referred to as "they" throughout the game. Canonically, there aren't many gateways to being able to find romance between their relationship either.

Popular rival ships for the pairing include Soriel and Charisk. There are also people who choose not to ship Frisk or Sans with anyone.

On AO3, Frans is the most written ship for Frisk and the fourth most written ship for Sans. It is also the sixth most written ship in the Undertale (Video Game) tag.

Fandom
FAN FICTION

Sans/Frisk on FanFiction.Net

DEVIANTART

Trivia

 * Frisk and Sans both appear to be left-handed.
 * Frisk's Official Tarot Card is "The Fool" while Sans' is "Judgement". The Fool represents beginnings, innocence, spontaneity, and being a free spirit but when reversed it means holding back, recklessness, and taking risks. This applies to Frisk because of their journey throughout the Underground. Judgement represents judgement, rebirth, inner calling, and absolution but in reverse it stands for self-doubt, inner critic, and ignoring the call. This applies to Sans because he judges Frisk at the end of the game. The result depends on which run the player decides to take.