NPCs/Waterfall

Echo Flower Explainer (1)
This fish-like monster will inform the protagonist of the Echo Flowers, which fill the marsh. If the protagonist speaks to the Echo Flower next to him before talking to him, the flower will repeat him stating how he feels that explaining the Echo Flower is his only purpose.

When talking to him after the Echo Flower says this, he will say "Never trust a flower," implying his embarrassment and resentment at being outed for what he feels is his sole purpose in life. He also states that mistrusting flowers are "one of the constants of this world," which is possibly an allusion to Flowey.

"Loren" (2)
This curious monster will ask the protagonist an assortment of questions about stars. Bringing an umbrella to them will prompt different dialogue.

Colin MacDougall created them.

Ferry (3)
Ferry Monster is a monster that appears in Waterfall. The only part of it that is visible is a small flat pink face, with an expression comparable to the ":3" emote. Using this monster, the protagonist can travel from one part of Waterfall to another. After each trip, the monster gives the protagonist 3G for stepping on their face and thanks them. Ferry will do this an infinite amount of times, and as such is a source of grinding for G (though not very efficient).

Onionsan (4)
Onionsan is a large aquatic monster that lives in Waterfall. They make anime-esque faces and have a rounded upper body that resembles an onion. They will also follow the protagonist throughout their room to keep up a conversation.

Onionsan claims that Waterfall is their "Big Favorite," although they express concern about the water getting very shallow as of late. Onionsan is also very lonely, as shown by their desperation to engage the protagonist in conversation. They explain that all their friends moved to a crowded aquarium in the city, saying that they cannot join them because the aquarium is full. Despite this, Onionsan tries to maintain a positive outlook, saying that Undyne will fix everything and that someday they will get out and live in the ocean.

When walking through their area a second time, Onionsan tells the protagonist that they are starting a band called the "Red Hot Chibi Peppers" despite it not knowing how to sing or play instruments. Onionsan asks the protagonist whether or not they think the band will become famous. Upon choosing "No," Onionsan will descend into the water, not surfacing if the protagonist re-enters the room. If the protagonist says "Yeah," Onionsan will continue to follow the protagonist throughout the room as usual. No more dialogue will occur until the protagonist reaches the True Pacifist ending.

Going back to Onionsan during the True Pacifist Route epilogue will trigger a little extra dialogue, Onionsan stating that if word got to them that the surface was open to monsters, they would be the first to tell Frisk. Going a second time would have them say "It's gotta be any day now!"

In the True Pacifist Ending Credits, Onionsan can be seen happily lounging in the water on the beach.

Clam Girl (5)
This rare NPC only appears when the Fun Value is between 80 and 89, and LV is under 8. She can be found near Napstablook's house. She talks about her neighbor, Suzy (who is never seen in-game ), and affirms that the protagonist should become friends with her. She notes the fact that the protagonist has no knowledge of where Suzy is, but insists that fate will find a way regardless. Post game dialogue with her depends on if the protagonist stopped to talk to her earlier. If the protagonist did, she gives an uplifting speech and their neighbor's blessing. If the protagonist walked by her, she states that she was going to tell the protagonist about her neighbor, but fate has decided that she should not do so.

In the 1.001 patch, Clam Girl will also say "In life's grand scheme, she might be why you came here in the first place..." which may also imply that Suzy might be someone whom the protagonist has met on the surface, and therefore, a human.

Small Bird (6)
This tiny but determined bird will carry the protagonist from one side of the room to the other. Its own special song plays when it does so.

According to Undyne when called in the room, the bird will carry anyone, and will not say no. She also says it never even thinks of giving up. Undyne was carried by the bird when she was younger for a whole hour. The bird is rather strong, as it can carry a human over a gap as seen when it carries the protagonist. Undyne demands the protagonist to cherish it.

In the Genocide Route, the bird does not appear. In the True Pacifist Ending Credits, the bird can be seen flying above Papyrus.

If the protagonist is carrying an umbrella, the text "Umbrellas and birds. A bad combination." appears. This prevents the protagonist from carrying the umbrella to other areas of Waterfall and the rest of the Underground.

Snails
These snails reside in Blook Family Snail Farm.
 * Snail 1 appears to have an extended nose and a mustache. They tell the protagonist to keep headstrong and reach far on their journey, most of their dialogue a pun on words like "long" and "extended," relating to their nose.
 * Snail 2 lies on its back with a suit and a shell on its stomach. They remark of how they were "long overdue for a second house."
 * Snail 3 seems to be missing its shell (and is, therefore, a slug) and counts dollar bills. It seems that this snail sold its shell to Snail 2.

Bob
Bob is one of the four Temmies that sits near the entrance of Temmie Village. He seems to be a joke character since the Temmies found next to him speaks with a visual speech impediment, while Bob simply says "Hi. I'm Bob" in clean English. At the end of a True Pacifist Run, Bob will voice his thoughts about the barrier being broken. Speaking to him will prompt the response "This is a most pleasing development, no?"

He seems to be one of the few Temmies with the ability to speak clean English. The only other Temmie, who shows this difference is the shopkeeping Temmie, who will speak in clean English if the protagonist denies her offer to buy an item.

Ragel
When spoken to, Ragel does a seemingly what he calls a mysterious mushroom dance (complete with its own music). Its moves are walking side to side with arms bent in a right angle position that which change from up and down, always the opposite of the other. He keeps his head down, so the two dots of his nostrils look more like eyes, before lifting his head to reveal his real eyes. He then says something to the protagonist, which differs depending on the protagonist's actions during the game. Alexander Sward created him.
 * On a Neutral Route, if the protagonist has not killed any monsters, he worries about how he is supposed to get to the surface (even if the barrier is destroyed) since he is rooted to his spot.
 * If the protagonist has killed at least one monster, he suggests that the protagonist has sinned. Attempting to talk to him again after this will result in him telling the protagonist not to speak to him.
 * If the protagonist speaks to him after the barrier is opened in a True Pacifist Route, he says he is happy, as he has found someone who will move him to the surface. He then questions why the protagonist was expecting a more distressed explanation of his dance.

Elder Puzzler (7)
This cynical, aging monster will express their resentment of the puzzles of today. They insist that modern kids are hopeless, and will criticize the protagonist's attempt at their box puzzle. They tell the protagonist that they are young and still have hope, and no matter what way the player pushes the box, the elder always scolds them.

Papyrus holds much respect for the Elder Puzzler, as referenced to in Papyrus's phone call when in the room.

Summer Wine created them.