(undertale spoilers)

if one believes that the player is the one who influences most of the decisions in undertale, it might leave one feeling that frisk has no agency or depth as a character. as it turns out, frisk does an awful lot of things that the player has absolutely no control over. these actions change depending on whether chara is in control or not, suggesting that the neutral/pacifist actions that the player cannot control are actually frisk’s.

here is a list of most of frisk’s own choices. italicised points are actions emulated by chara.

• frisk attempts to think of something to say to toriel during the battle (as opposed to chara’s “not worth talking to”).
• if toriel has been killed previously, frisk will look at her before the battle “like [they] have seen a ghost”.
• if a route has been done or aborted after meeting sans previously, frisk will turn around to shake hands with sans before he tells them to turn around.

▶ frisk moves behind the conveniently-shaped lamp to hide from papyrus.

this action is significant because it’s the first major action that contrasts with chara. chara refuses to play along in the genocide route, but frisk is happy to go along with sans. after papyrus leaves, frisk steps out from the lamp on their own.

▶ frisk hears the snowman out and only takes one piece of it.

chara keeps taking pieces of the snowman until it’s just “a useless pile of snow”. in contrast, frisk lets the snowman finish its speech. if frisk agrees to take a piece, they only take one small piece that doesn’t disfigure the snowman when removed.

• there is no option to call the monster whose picture is on the fishing line. frisks decides not to on their own.
  
• doggo has no real reaction to frisk (he shivers in chara’s presence).
• frisk does not interrupt papyrus as he explains puzzles.
• before the date or hangout with papyrus, frisk follows him around snowdin before he enters his house.

▶ after checking the sink in papyrus’ house, revealing the annoying dog, frisk tries to catch him when papyrus asks them to.

PAPYRUS:
CATCH THAT MEDDLING CANINE!

although frisk fails to catch the dog, they put their best effort into trying to do so. the player cannot do anything here.

• when climbing on monster kid, they put care into being gentle with them.
  
• in the pacifist route, where frisk’s name is learned, choosing to hit the training dummy (mad dummy) will result in frisk lightly tapping it. frisk will “feel bad”.

▶ it’s implied that frisk responds in some way to monster kid affirming that they are, in fact, human.

MONSTER KID:
Yo… You’re human, right? Haha.
Man! I knew it!
…well, I know it now, I mean…

this is significant because, in the genocide route, chara makes a habit of not responding to anyone.

• during the hangout with undyne, after frisk looks inside the bone drawer and sees the annoying dog, they’ll immediately turn around to face the screen.
  
• frisk drinks undyne’s golden flower tea, but they’re hesitant to do so at first after being told it’s hot.
• apparently, frisk drinks all the tea, prompting undyne to attempt to get them some more.
• frisk turns to look at undyne when she leaps over to pick them up.
• before battling RG01 and RG02, frisk plays along and follows them around.
• when frisk is trapped in muffet’s web, the player can turn frisk in any direction until muffet appears, at which point frisk will turn to face her of their own accord.
• after mettaton’s coloured tile puzzle, frisk turns towards him.

▶ during the mtt hotel scene, when sans mentions that frisk hasn’t died a single time, frisk gives him some sort of “look”.

SANS:
hey, what’s that look supposed to mean?
am i wrong…?

based on sans’ reaction, the “look” is probably one of irritation. perhaps frisk scoffs at this a little.

• just as frisk is about to enter the long elevator that connects to new home, alphys asks frisk to stop. frisk stops and turns to face her.
  
• after alphys’ speech, frisk automatically turns back towards the elevator.

▶ when frisk runs from monsters, they do it with a smile.

during sans’ pacifist judgment, he mentions that frisk smiles when they flee from monsters, something we couldn’t have known up to this point. it speaks volumes about frisk’s friendly disposition. 

▶ reloading the game to just before sans’ judgment will cause frisk to wear a certain “look” during his speech.

perhaps frisk looked bored.

▶ reloading before the judgment once again will cause frisk to do something in order to get sans’ attention.

frisk wants to tell sans the secret codeword. it makes sense that frisk has done something to make him realise they have something to say.

▶ immediately after, frisk mentions something about a codeword to sans.

they must say this out loud, prompting sans to ask frisk to “speak a little louder”.

▶ frisk, in canon, on their own, without any prompt from the player, says, “i’m a stupid doodoo butt”.

SANS:
wow. i can’t believe you would say that.
not only is that completely infantile…
but it’s also my secret codeword.

frisk says the secret codeword out loud. sans seems to be enjoying his prank.

▶ with their own two lips, frisk says, in canon, on their own, with no prompt from the player, “i’m the legendary fartmaster”.

SANS:
wow.
that’s… uh… really childish.

frisk continues playing along.

▶ frisk might mention this being a secret secret codeword on their own, which sans corrects.

SANS:
whoever told you that is a dirty liar.
i don’t have a secret secret codeword.
however.
i do have a secret secret triple-secret codeword.
which you just said.
so, i guess you’re qualified.

something prompted sans to mention a “secret secret codeword”, and it was probably frisk.

• in the pacifist-neutral route, in the battle against asgore, the “talk” ACT will prompt frisk to beg asgore to stop fighting. if a monster has been killed before the asgore battle, the “talk” ACT will instead prompt a response of, “but there was nothing to say”.
  
• if frisk has died to asgore in a pacifist-neutral route, the first “talk” ACT will be replaced with frisk telling asgore that he killed them before. 
• in the neutral end, after flowey says he’ll tear frisk “to bloody pieces” and then pauses, frisk bravely steps forward.

▶ frisk walks extremely slowly to the bath monster in the true lab.

frisk can walk back out of the room at normal speed while the monster is still there, suggesting that frisk has some sort of fear of it and would rather not be in this room. 

• after each of the vhs tapes, frisk turns around to face the screen.
  

▶ in the pacifist route, after flowey captures all of frisk’s friends in his vines, it is implied that frisk asks flowey why he’s doing this.

flowey interrupts his speech as if he’s been asked a question, and then repeats said assumed question.

▶ during the fight with asriel, frisk attempts to move and reach their save file on their own.

although it’s normally the player who has the option to save and load the game, if a save file is present in undertale, frisk will try to reach it themself.

these are all things that frisk does on their own without any prompt from the player whatsoever. unlike the impatient chara, frisk is polite and won’t move while others are speaking. all together, these actions paint a picture of a kind individual who cares about making others happy.