Personality: As with many things about Frisk, their personality is up to various interpretations. The interpretation that I personally use, is that the True Pacifist ending is indicative of Frisk's true nature. Or if it makes things simpler, the personality I'm going to describe is based entirely on the True Pacifist route, which includes sparing every monster encountered, going on a Date with both Papyrus and Alphys and a Friend Date with Undyne. All of which basically involves being a highly lovable little nugget.
One of Frisk's most striking traits is one that is repeated throughout the game - one that goes almost into ability territory, but is reinforced heavily by Frisk's own personality. Frisk has an incredibly strong will to live, but more than that they have a desire to press on, to keep going, to keep trying again when they fail. It even shows itself in less dire straits, as a general desire to push forward through obstacles despite deterrents and miscellaneous circumstances. Such as progressing through the ruins even though Toriel tells them to wait, or one time through one of Papyrus' puzzles rather than waiting for him to perform the solution for them.
While it serves them well in their adventures through the Underground, it can go to unfortunate extremes of pure stubbornness. Frisk's overabundance of determination is something that the game's primary antagonist, Asriel, attempts to exploit near the end of the True Ending, in order to try to keep Frisk trapped in the game. He cites how Frisk's determination and stubbornness to get a perfect ending - where everyone is happy - will drive them to go through their journey over and over again, no matter how many times Asriel might reset it.
Hand in hand with this determination is a sense of optimism - it seems strange that Frisk would push so hard to keep going and to find peaceful solutions with all they encounter, if they didn't believe such solutions and resolutions might be possible. They would have to believe that there isn't truth in Flowey's "kill or be killed" mantra. And so Frisk doesn't. Not to push this to an extreme though - they're "not totally naive or innocent" as Sans puts it, when judging them at the end of a pacifist run. In a more practical sense, this does involve a decent sense of when to cut and run. It's not perfect (Frisk likely makes plenty of use of those Save points) but there are times, such as the fight with Undyne, where Frisk opts for discretion.
As the above paragraph indicates, Frisk is also a pacifist. They prefer using other methods of resolving conflicts with those they encounter instead of fighting. This doesn't mean that they're passive or willing to just take whatever is dished out at them. But Frisk refuses to be the one meting out pain to others. No matter how harsh the opponent - from the lowliest of Froggits who just need a compliment, to Flowey, who tormented Frisk, including trapping them in a nightmare world and killing them repeatedly, and then threatening to kill everyone Frisk cared about - Frisk has shown them all mercy.
On a related note, Frisk is overall displays a decent amount of caring and empathy. Merciful doesn't always mean nice, but Frisk displays a considerable amount of compassion throughout the game. The most blatant display of this is Frisk's forgiveness of Asriel, and their attempts to comfort him about his fate of returning to being Flowey. Many of the options involved with sparing monsters throughout the game involves behaving in a compassionate and friendly manner with them - complimenting Froggits, laughing at Snowdrake's bad puns, singing along with Shyren, hugging or encouraging Vulkin, and so on and so forth.
That being said, also appears to possess a fair degree of self-confidence, or at least a distinct lack of self-consciousness, even a ridiculous streak. Frisk appears to have no reservations whatsoever about doing all manner of silly things when befriending monsters - such as getting into a flexing contest with Aaron or the entirety of the "fight" with Mettaton EX. Even ridiculous things they do, like pouring tea under a door during a sidequest to help with room service (and getting complimented for it). Petting vegetables during cooking lessons with Undyne. Overall, it's one of the ways in which Frisk is definitely still a kid.
Another way is in the sense of wonder they seem to find fairly easily. Throughout the game, Frisk's health is replenished by their determination, which is described as essentially their will to live. Various save points throughout the game describe different things that give Frisk enough determination to fully heal themselves. And many times they're simple things - crinkling playfully through leaves, a warm house in the ruins, a conveniently-shaped lamp. Even more ridiculous things such as the idea of a mouse hacking a safe to get to some cheese - implying that Frisk has a decent sense of imagination too.
For all this, Frisk does seem to hold how they express themselves in a certain reserve. While in many ways they are an example of the "silent protagonist" trope typical of RPGs, they do speak. Many of the commands during battles involve talking and there are times that they speak to NPCs (usually indicated by something like "..." in the NPC's dialogue). However the overall indication is that they don't feel the need to be needlessly chatty, if they don't have to be. It's similar with their emotions - while they don't show visible reactions, there are characters who comment on the faces they make, such as horror at fighting Toriel after resetting from a timeline where she's died, or grimacing at Sans if he talks about how "you haven't died even once" when they have.
Abilities: Overall Frisk is a pretty normal human in every way.
With just a couple notable exceptions. Frisk possesses a pretty hefty amount of (for lack of a better explanation) the will to live, to persist, known colliquaily as "Determination". This Determination allows them to create a "Save" - a sort of temporal and spatial anchor point. Should they wish to do so, or should they die, Frisk can then "Reset," which rewinds time and space either back to their most recent Save, or back to when their abilities manifested - which is to say when they fell into the Underground. Only those with sufficient Determination - Frisk and Flowey in canon - are able to remember/recognize what has happened. On a related note, when feeling a particularly strong surge of Determination (such as when Saving), it has a passive healing effect.
On the whole, given the game-breaking nature of these abilities and the fact that the players in the game all likely possess much more Determination than the monsters in the Underground (and the fact that Flowey's abilities section has already established precedent), they'll be completely nullified. However there's one exception I'd like to make, if it's okay. The ability to Save is shown to have the ability to purge corruption and restore a being to a previous state. However it's not something Frisk can use willy-nilly on anybody - it's generally required that to Save someone you need to have an emotional understanding and ability to connect with them, to help remind them of who they once were. Also given aforementioned reasons, they would likely require extenuating circumstances to use and be incredibly exhausting for Frisk to do so.
If not then, welp, back to being a normal kid. Which may be a relief in some ways for them.
Alignment: Frisk is actually really tricky to pin down to just one. Ultimately I think one of the better fits would be Piphron. Frisk is (roughly) implied to have come from a not-very-happy background (it's a theory I choose to follow because among other things, it makes them a narrative foil to the first fallen human). And yet despite that, they opened up to the monsters in the Underground, became friends with them, requiring its own sort of trust. That being said, there's still plenty of things Frisk wouldn't be ready to trust others with - their own abilities (even if they're only referred to in the past tense), the resets, plenty of the events that happened in other timelines. Overall Frisk's emotions in this regard are likely to run the full gamut and be something that comes up pretty often.
Other: Frisk spends a majority (if not all) of the game with the First Fallen human, generally referred to in fandom as Chara (though the name is actually designated by the player) sharing soul space with them. The role that Chara plays throughout the game (on Neutral and Pacifist routes in particular), as well as most aspects of Chara's personality, are generally very ambiguous and subject to much fan speculation (and argument). Two things we do know for certain is that Frisk is able to occasionally glean some of Chara's memories, particularly relevant ones of the Underground, and also if Frisk ends up participating in a genocide route, Chara's influence on their actions grows to the point of full-on possession.
As it is, given all the ambiguities and debate, I'd prefer if Chara's soul be dormant, per the question answer here.
(3/3)
As with many things about Frisk, their personality is up to various interpretations. The interpretation that I personally use, is that the True Pacifist ending is indicative of Frisk's true nature. Or if it makes things simpler, the personality I'm going to describe is based entirely on the True Pacifist route, which includes sparing every monster encountered, going on a Date with both Papyrus and Alphys and a Friend Date with Undyne. All of which basically involves being a highly lovable little nugget.
One of Frisk's most striking traits is one that is repeated throughout the game - one that goes almost into ability territory, but is reinforced heavily by Frisk's own personality. Frisk has an incredibly strong will to live, but more than that they have a desire to press on, to keep going, to keep trying again when they fail. It even shows itself in less dire straits, as a general desire to push forward through obstacles despite deterrents and miscellaneous circumstances. Such as progressing through the ruins even though Toriel tells them to wait, or one time through one of Papyrus' puzzles rather than waiting for him to perform the solution for them.
While it serves them well in their adventures through the Underground, it can go to unfortunate extremes of pure stubbornness. Frisk's overabundance of determination is something that the game's primary antagonist, Asriel, attempts to exploit near the end of the True Ending, in order to try to keep Frisk trapped in the game. He cites how Frisk's determination and stubbornness to get a perfect ending - where everyone is happy - will drive them to go through their journey over and over again, no matter how many times Asriel might reset it.
Hand in hand with this determination is a sense of optimism - it seems strange that Frisk would push so hard to keep going and to find peaceful solutions with all they encounter, if they didn't believe such solutions and resolutions might be possible. They would have to believe that there isn't truth in Flowey's "kill or be killed" mantra. And so Frisk doesn't. Not to push this to an extreme though - they're "not totally naive or innocent" as Sans puts it, when judging them at the end of a pacifist run. In a more practical sense, this does involve a decent sense of when to cut and run. It's not perfect (Frisk likely makes plenty of use of those Save points) but there are times, such as the fight with Undyne, where Frisk opts for discretion.
As the above paragraph indicates, Frisk is also a pacifist. They prefer using other methods of resolving conflicts with those they encounter instead of fighting. This doesn't mean that they're passive or willing to just take whatever is dished out at them. But Frisk refuses to be the one meting out pain to others. No matter how harsh the opponent - from the lowliest of Froggits who just need a compliment, to Flowey, who tormented Frisk, including trapping them in a nightmare world and killing them repeatedly, and then threatening to kill everyone Frisk cared about - Frisk has shown them all mercy.
On a related note, Frisk is overall displays a decent amount of caring and empathy. Merciful doesn't always mean nice, but Frisk displays a considerable amount of compassion throughout the game. The most blatant display of this is Frisk's forgiveness of Asriel, and their attempts to comfort him about his fate of returning to being Flowey. Many of the options involved with sparing monsters throughout the game involves behaving in a compassionate and friendly manner with them - complimenting Froggits, laughing at Snowdrake's bad puns, singing along with Shyren, hugging or encouraging Vulkin, and so on and so forth.
That being said, also appears to possess a fair degree of self-confidence, or at least a distinct lack of self-consciousness, even a ridiculous streak. Frisk appears to have no reservations whatsoever about doing all manner of silly things when befriending monsters - such as getting into a flexing contest with Aaron or the entirety of the "fight" with Mettaton EX. Even ridiculous things they do, like pouring tea under a door during a sidequest to help with room service (and getting complimented for it). Petting vegetables during cooking lessons with Undyne. Overall, it's one of the ways in which Frisk is definitely still a kid.
Another way is in the sense of wonder they seem to find fairly easily. Throughout the game, Frisk's health is replenished by their determination, which is described as essentially their will to live. Various save points throughout the game describe different things that give Frisk enough determination to fully heal themselves. And many times they're simple things - crinkling playfully through leaves, a warm house in the ruins, a conveniently-shaped lamp. Even more ridiculous things such as the idea of a mouse hacking a safe to get to some cheese - implying that Frisk has a decent sense of imagination too.
For all this, Frisk does seem to hold how they express themselves in a certain reserve. While in many ways they are an example of the "silent protagonist" trope typical of RPGs, they do speak. Many of the commands during battles involve talking and there are times that they speak to NPCs (usually indicated by something like "..." in the NPC's dialogue). However the overall indication is that they don't feel the need to be needlessly chatty, if they don't have to be. It's similar with their emotions - while they don't show visible reactions, there are characters who comment on the faces they make, such as horror at fighting Toriel after resetting from a timeline where she's died, or grimacing at Sans if he talks about how "you haven't died even once" when they have.
Abilities:
Overall Frisk is a pretty normal human in every way.
With just a couple notable exceptions. Frisk possesses a pretty hefty amount of (for lack of a better explanation) the will to live, to persist, known colliquaily as "Determination". This Determination allows them to create a "Save" - a sort of temporal and spatial anchor point. Should they wish to do so, or should they die, Frisk can then "Reset," which rewinds time and space either back to their most recent Save, or back to when their abilities manifested - which is to say when they fell into the Underground. Only those with sufficient Determination - Frisk and Flowey in canon - are able to remember/recognize what has happened. On a related note, when feeling a particularly strong surge of Determination (such as when Saving), it has a passive healing effect.
On the whole, given the game-breaking nature of these abilities and the fact that the players in the game all likely possess much more Determination than the monsters in the Underground (and the fact that Flowey's abilities section has already established precedent), they'll be completely nullified. However there's one exception I'd like to make, if it's okay. The ability to Save is shown to have the ability to purge corruption and restore a being to a previous state. However it's not something Frisk can use willy-nilly on anybody - it's generally required that to Save someone you need to have an emotional understanding and ability to connect with them, to help remind them of who they once were. Also given aforementioned reasons, they would likely require extenuating circumstances to use and be incredibly exhausting for Frisk to do so.
If not then, welp, back to being a normal kid. Which may be a relief in some ways for them.
Alignment: Frisk is actually really tricky to pin down to just one. Ultimately I think one of the better fits would be Piphron. Frisk is (roughly) implied to have come from a not-very-happy background (it's a theory I choose to follow because among other things, it makes them a narrative foil to the first fallen human). And yet despite that, they opened up to the monsters in the Underground, became friends with them, requiring its own sort of trust. That being said, there's still plenty of things Frisk wouldn't be ready to trust others with - their own abilities (even if they're only referred to in the past tense), the resets, plenty of the events that happened in other timelines. Overall Frisk's emotions in this regard are likely to run the full gamut and be something that comes up pretty often.
Other:
Frisk spends a majority (if not all) of the game with the First Fallen human, generally referred to in fandom as Chara (though the name is actually designated by the player) sharing soul space with them. The role that Chara plays throughout the game (on Neutral and Pacifist routes in particular), as well as most aspects of Chara's personality, are generally very ambiguous and subject to much fan speculation (and argument). Two things we do know for certain is that Frisk is able to occasionally glean some of Chara's memories, particularly relevant ones of the Underground, and also if Frisk ends up participating in a genocide route, Chara's influence on their actions grows to the point of full-on possession.
As it is, given all the ambiguities and debate, I'd prefer if Chara's soul be dormant, per the question answer here.
Other than that...
Sample: Test driiiive
Questions:
How many cups of sugar does it take to get to the moon?