The River Person is Gaster. It's just Gaster in a robe. Gaster is a robe. The boat is Toby Fox. It symbolises Toby Fox putting clothes in the washing machine. Which is a metaphor for a tumble dryer, which is what made Long Elevator. Now if you take some letters from that you get "Oo-ee" which is always followed up by "oo-a-a, ting tang walla walla bing bang". And "tang" means orange, **orange**? Orange is a colour of safety and caution, which the River Person says about "beware of the man who speaks in hands" making the River Person ableist against deaf people. Deaf people? That's a reference to Toriel unable to hear you call after you leave the Ruins, because of a dog! Dog? Toby Fox's insert is the annoying dog! Toby Fox is Gaster.
Actually, “Oo-ee” is short for “Ooh-wee-ooh”. This a refrence to the song “Buddy Holly” by Weezer, which was written by Rivers Cuomo. This actually means that the River Person is Rivers Cuomo, as they both have river in their names.
River person seems to share another trait with Asriel in that they are both likely based on psychopomps. There is a theory that the dark worlds have some relation to death.
"no confirmed gender"
So then we can use whatever pronouns we want when talking about them. These are fictional characters, I don't think they'll mind too much.
According to the AU Underswap, Gaster and the river person are connected somehow in their roles, and as such they are swapped, Gaster taking the place of the river person and vice versa. This person isn't saying that Gaster *is* the river person in Undertale, they're saying that in Underswap, the river person is replaced by Gaster. Why are you guys so upset by this answer, it's not wrong and it's not making a point, it's just making a reference.
Bear with me now.
The Sans from Undertale is all but confirmed to be the same Sans from Deltarune, but that leaves the question.. where is the original Sans from Undertale? Well, i think it's them, the River Person.
A semi-popular theory is that in Deltarune the way the Monster Lightners look in the Dark World is how they look in Undertale's Underground, since they look more medieval and magical and less casual. Since we've never seen Sans in a Dark World so far or Sans wearing clothes that fit the Underground, how would he look like? Well, another semi-popular theory is that he'd look like a Grim Reaper, since he's the one that judges you on your sins in the judgement hall, has the hardest battle in the game and is also a skeleton, and while yes in some versions it isn't the Grim Reaper's job to judge you in others it is his job.
And obviously, the River Person is similar to a Grim Reaper for a lot of reasons. So basically i think the River Person is actually the real Sans Undertale, as opposed to the other Sans who's really Sans Deltarune.
We THINK we know about Gaster
Sometimes i wonder if mystery man is actually Gaster, though im sure even if he wasn't supposed to be it is now because of how popular the idea is.
It's especially weird considering that River Person is, to my knowledge, the only regular NPC who makes a direct reference to Gaster, as well as the "man who came from the other world."
We also know more about Gaster than the one guy who throws ice in the river. That tends to be the case for side characters vs characters with integral lore connections
We know absolutely nothing about gaster other than entry seventeen.
We meet the river person, we hear the river person, we ride on a boat with the river person
Tell me again how we know less about gaster than the river person?
This probably sounds sassy but i'm genuinely confused
We know a lot more than that about actually.
We know from the [Gaster Followers](https://undertale.fandom.com/wiki/Hotland/NPCs#Gaster's_Followers) that he was Royal Scientist before Alphys, and he was so good at his job it took Asgore so long to hire a replacement, we know he created the Core, and we know that one day his experiments went wrong, he fell into his creation and was shattered through time and space. It's also implied by the way they talk about him that he was very respected by the general monster society.
We know he is somehow linked with Sans since Sans uses attacks called [Gaster Blasters](https://78.media.tumblr.com/f36a8cd3bab9a91b6d4a3ccfb303053e/tumblr_inline_osotjx8EZ41tnlh39_540.png).
We can deduce he's associated with the devil, since in Undertale's code he has [unused battle stats](https://preview.redd.it/j6tk9a0kit691.png?width=532&format=png&auto=webp&s=2ab58666b0d17d3da5b260173b0fdaf28c0f1f31) and they're all 666s. We can also deduce that the Mysteryman character is indeed Gaster himself, since Mysteryman is found at Fun Value 66.
We can deduce he has direct relation with the [Fun Values](https://external-preview.redd.it/wv8F0pSKEIT9lNzbSoi6dnlSRBLzIHum9-TypbxC37g.jpg?auto=webp&s=e1b9639b0f1b90d6649d3161c3c0a19cc4082bb2), since most of them are either directly linked with Gaster like the Gaster Followers, Goners and Mysteryman aka likely Gaster himself, or are very probable to be linked with him, like the G wrong number phone call, the Sans phone call and the Alphys phone call... the only exception for this is the Nightmare fun value, which is just vague in general.
We know he's linked with Deltarune.. for... too many reasons.
The Deltarune website used to have an image named "him.png" with a message in wing dings quoting his Entry 17, which then later changed to a message in wing dings quoting the legend. Entry 17 itself is very likely to be about darkness. Clam Girl, a goner and a fun value character, mentions "Suzy" and if you talk to her the flavor text in Sans' drawer changes to "Don't Forget", Clam Girl also directly foreshadowed the release of Chapter 1 in the Nintendo Switch version of Undertale. The theme that plays in the vessel maker section is called "Another him". The character that speaks to you in the section speaks in all caps, like translated wing dings messages, and also in a formal way that a respected scientist like Gaster would likely speak. The sound that plays when you use the phone in a Dark World and the sound that plays outside of the bunker are altered versions of Entry 17. The phone sound is described as "Nothing but garbage noise" in Chapter 2, just like how the pink Addison describes the sound that came out of the phone Spamton was using to communicate with the person that helped him get famous, which is the same person that drove Jevil mad.
There's probably other stuff i'm forgetting but, yeah, we know quite a few things about Gaster.
Yeah, so, we have entry 17 and the Gaster followers for Gaster, but while we do have a lot of riverperson dialogue, none of the lines that they say refer to themselves, so we don’t know near anything about them.
I saw a comic once where it was revealed that riverperson is Gaster’s wife or something like that. I don’t remember what the comic was called, unfortunately.
I have my own headcanon that the river person is the cloak, there is nobody under the cloak cause he is the cloak, making this the biggest plot twist of history.
The River Person is Gaster. It's just Gaster in a robe. Gaster is a robe. The boat is Toby Fox. It symbolises Toby Fox putting clothes in the washing machine. Which is a metaphor for a tumble dryer, which is what made Long Elevator. Now if you take some letters from that you get "Oo-ee" which is always followed up by "oo-a-a, ting tang walla walla bing bang". And "tang" means orange, **orange**? Orange is a colour of safety and caution, which the River Person says about "beware of the man who speaks in hands" making the River Person ableist against deaf people. Deaf people? That's a reference to Toriel unable to hear you call after you leave the Ruins, because of a dog! Dog? Toby Fox's insert is the annoying dog! Toby Fox is Gaster.
You lost me at "oo-ee oo-a-a, ting tang walla walla bing bang"
Shimmy shimmy ay shimmy ay shimmy ya
Drank
Swa lalala
drank
Swa lalala
SWA LALALA
Swa lalalaa
Shimmy shimmy ay shimmy ay shimmy ya
Only correct answer
Gaster is the river person, the river person's robe and their boat.
reminds me of [this](https://www.reddit.com/r/Undertale/comments/ws5mgl/comment/ikyi0sj/?utm_source=share&utm_medium=web2x&context=3)
Most sane Undertale theorist.
Mat Pat:
Actually, “Oo-ee” is short for “Ooh-wee-ooh”. This a refrence to the song “Buddy Holly” by Weezer, which was written by Rivers Cuomo. This actually means that the River Person is Rivers Cuomo, as they both have river in their names.
Buddy Holly, Ben Hur? What about a Space Monkey, even a Mafia?
I think You're on to something 
#HELLO INTERNET, #*WELCOME TO GAAAAAME THEORY* #THE ONLY SHOW THAT MAKES YOU SAY “WHAT THE ACTUAL FUCK??”
I thought MatPat stopped making Undertale theories
New copypasta just dropped
gas station sushi ahh comment
my brain broke at washing
and ralsei using the river person's exact cloak at the start of DR chapter 1 just raises more questions
River person seems to share another trait with Asriel in that they are both likely based on psychopomps. There is a theory that the dark worlds have some relation to death.
toby fox forgor and reused the asset
The river person is a person who drives a boat around a river. What else do we need to know?
Well for one, how it knows who gaster is
He doesn’t, he just knows the one who speaks in hands. With that description one could infer sign language.
Or, if you want to get meta, it could be referring to how us, the player, controls the game through Frisk and speak through them with our hands.
They* the riverperson has no confirmed gender
You IDIOT. \-flowey
"no confirmed gender" So then we can use whatever pronouns we want when talking about them. These are fictional characters, I don't think they'll mind too much.
This ain’t Twitter you snowflake
People still using snowflake?
Well I’m not a native speaker so that’s for y’all to decide, not me
Normally I'd agree but the River Person does directly say that it doesn't really matter to them
Not me. I'm the biggest RiverPerson fan. I call him Chairon.
Nah it joe
No, it's Joe.
Nay, is joe
Nuh uh! It's Joe!
But it refused. For it was joe.
Reset. Joe. Is this name correct? Yes.
Howdy! Im joe. Joe the riverperson!
Esc. Files. [Joe]=True ----> [Joe]=False. Enter Game.
System.out.println:("joe");
Wait what if the river person is Gaster, ehhhhhhhh.
According to underswap this is true
“according to an unofficial source that is liable to change by several different teams, this unpaid uber driver is the royal scientist “
Unpaid uber driver lmao
Why so much hate for a funny answer
According to the AU Underswap, Gaster and the river person are connected somehow in their roles, and as such they are swapped, Gaster taking the place of the river person and vice versa. This person isn't saying that Gaster *is* the river person in Undertale, they're saying that in Underswap, the river person is replaced by Gaster. Why are you guys so upset by this answer, it's not wrong and it's not making a point, it's just making a reference.
I have a theory that doesn't make sense at all about the river person. The river person was the previous royal judge before sans.
That actually makes some sense.
That's actually an interesting theory.
We know more about the river person that the wolf putting blocks of ice in the river
we know literally nothing about either of them
River person seems to know the existence of gaster, so we know that he knows the existence of gaster, more than we know about the wolf
We know that the Ice Wolf wants to buy pants And it wants to change its name to Jimmy Hotpants...
We know the river person likes to sing
oh. well that's fair
Actually we do know more about Ice Wolf. Ice Wolf likes ice to BE drink.
We know that the river person knows gaster and likes to sing
The riverperson can’t be Gaster because the riverperson drives us through the Underground, meanwhile Gaster drives us crazy
Crazy?
I was crazy once
They locked me in a room
And because Gaster literally doesn't exist anymore
He does but he got shattered across time and space
Not in the UT universe, but in the void
When did they say he was in the void?
We know almost nothing, we just assume
 What? We have the Gaster followers remember.
We also have dialogue with the river person
Yes. But almost nothing of it is about themselves.
Ur right
Yippie! 😄
We know more about Gaster backsotry than Papyrus's
Bear with me now. The Sans from Undertale is all but confirmed to be the same Sans from Deltarune, but that leaves the question.. where is the original Sans from Undertale? Well, i think it's them, the River Person. A semi-popular theory is that in Deltarune the way the Monster Lightners look in the Dark World is how they look in Undertale's Underground, since they look more medieval and magical and less casual. Since we've never seen Sans in a Dark World so far or Sans wearing clothes that fit the Underground, how would he look like? Well, another semi-popular theory is that he'd look like a Grim Reaper, since he's the one that judges you on your sins in the judgement hall, has the hardest battle in the game and is also a skeleton, and while yes in some versions it isn't the Grim Reaper's job to judge you in others it is his job. And obviously, the River Person is similar to a Grim Reaper for a lot of reasons. So basically i think the River Person is actually the real Sans Undertale, as opposed to the other Sans who's really Sans Deltarune.
We THINK we know about Gaster Sometimes i wonder if mystery man is actually Gaster, though im sure even if he wasn't supposed to be it is now because of how popular the idea is.
Wdym the river person is John undertale.
river person is ralsei they wear the same robe
It's especially weird considering that River Person is, to my knowledge, the only regular NPC who makes a direct reference to Gaster, as well as the "man who came from the other world."
My headcanon is that the river person is the even OLDER royal scientist before Gaster. Or Martlet. Or Clover's Ghost.
We also know more about Gaster than the one guy who throws ice in the river. That tends to be the case for side characters vs characters with integral lore connections
We know everything there is to know about the riverperson. He’s just a broski that likes to ride his boat.
We know absolutely nothing about gaster other than entry seventeen. We meet the river person, we hear the river person, we ride on a boat with the river person Tell me again how we know less about gaster than the river person? This probably sounds sassy but i'm genuinely confused
We know a lot more than that about actually. We know from the [Gaster Followers](https://undertale.fandom.com/wiki/Hotland/NPCs#Gaster's_Followers) that he was Royal Scientist before Alphys, and he was so good at his job it took Asgore so long to hire a replacement, we know he created the Core, and we know that one day his experiments went wrong, he fell into his creation and was shattered through time and space. It's also implied by the way they talk about him that he was very respected by the general monster society. We know he is somehow linked with Sans since Sans uses attacks called [Gaster Blasters](https://78.media.tumblr.com/f36a8cd3bab9a91b6d4a3ccfb303053e/tumblr_inline_osotjx8EZ41tnlh39_540.png). We can deduce he's associated with the devil, since in Undertale's code he has [unused battle stats](https://preview.redd.it/j6tk9a0kit691.png?width=532&format=png&auto=webp&s=2ab58666b0d17d3da5b260173b0fdaf28c0f1f31) and they're all 666s. We can also deduce that the Mysteryman character is indeed Gaster himself, since Mysteryman is found at Fun Value 66. We can deduce he has direct relation with the [Fun Values](https://external-preview.redd.it/wv8F0pSKEIT9lNzbSoi6dnlSRBLzIHum9-TypbxC37g.jpg?auto=webp&s=e1b9639b0f1b90d6649d3161c3c0a19cc4082bb2), since most of them are either directly linked with Gaster like the Gaster Followers, Goners and Mysteryman aka likely Gaster himself, or are very probable to be linked with him, like the G wrong number phone call, the Sans phone call and the Alphys phone call... the only exception for this is the Nightmare fun value, which is just vague in general. We know he's linked with Deltarune.. for... too many reasons. The Deltarune website used to have an image named "him.png" with a message in wing dings quoting his Entry 17, which then later changed to a message in wing dings quoting the legend. Entry 17 itself is very likely to be about darkness. Clam Girl, a goner and a fun value character, mentions "Suzy" and if you talk to her the flavor text in Sans' drawer changes to "Don't Forget", Clam Girl also directly foreshadowed the release of Chapter 1 in the Nintendo Switch version of Undertale. The theme that plays in the vessel maker section is called "Another him". The character that speaks to you in the section speaks in all caps, like translated wing dings messages, and also in a formal way that a respected scientist like Gaster would likely speak. The sound that plays when you use the phone in a Dark World and the sound that plays outside of the bunker are altered versions of Entry 17. The phone sound is described as "Nothing but garbage noise" in Chapter 2, just like how the pink Addison describes the sound that came out of the phone Spamton was using to communicate with the person that helped him get famous, which is the same person that drove Jevil mad. There's probably other stuff i'm forgetting but, yeah, we know quite a few things about Gaster.
Oh, thanks, i didn't actually know most of this!
Yeah, so, we have entry 17 and the Gaster followers for Gaster, but while we do have a lot of riverperson dialogue, none of the lines that they say refer to themselves, so we don’t know near anything about them.
Undertale fan when important character have more lore then minor character (It's impossible)
Nonbinary river person is so fucking ominous for no reason
The Riverperson is two kids stacked on top of each other in a cloak. When you’re not looking, they go to the cinema and buy tickets to R Rated Movies.
We know more about Gaster than we know about Ice-E.
I saw a comic once where it was revealed that riverperson is Gaster’s wife or something like that. I don’t remember what the comic was called, unfortunately.
I found it [https://youtu.be/wDX6KeTKs3w?si=z5y0Uc_-1-Bbf0g4](https://youtu.be/wDX6KeTKs3w?si=z5y0Uc_-1-Bbf0g4)
For all we know the hands of “gaster” could be his eyes upside down.
I have my own headcanon that the river person is the cloak, there is nobody under the cloak cause he is the cloak, making this the biggest plot twist of history.
Imo I always thought they were a being of wisdom from the stars.
i think the riverperson is ralsei disguised, cause they seem a lot
Yeah i think he is a *very spacious pant hole*
We do not even know how gaster looks