Monster Kid

Monster Kid is a young monster who will stop at nothing to see their idol Undyne in action.

Appearance
Monster Kid is a yellow monster, with no arms, a tail, and spines on the back of their head. They have markings under their eyes, which are presumed to be black eyes. One of the markings is bigger than the other. They wear a yellow shirt with brown stripes.

Personality
They look up to Undyne as a role model. They are an innocent monster who assumes the energetic attitude that pervades most of their actions. They seem to be a bit naive, as well as a bit clumsy, as they trip frequently.

Despite being notably frightened by the protagonist during the Genocide Route (once they discover the protagonist's intentions, at least), they stand up to the protagonist with an intense expression, ready to protect the Underground.

Neutral Route
Monster Kid first meets the protagonist in Snowdin. They note how both of them are wearing striped shirts, so they both must be children. However, Kid does not seem to notice that the protagonist is a human child.

They later sneak out of Snowdin to explore the Waterfall, looking for Undyne. They follow the protagonist, not knowing that Undyne is searching for them because they are a human, and feel a little jealous that they receive so much attention. Monster Kid eventually finds out that the protagonist is a human, and reluctantly considers them an enemy. They try to say something mean to the human, in an attempt to become enemies, but feel bad for it and leave.

Just as the kid takes off, they trip and hang off a ledge. Undyne approaches and the player is given a choice: After fighting Undyne, Monster Kid can be found in Snowdin. Depending on the protagonist actions, they will either resent or idolize the protagonist.
 * Help them get up the ledge
 * Monster Kid defends the protagonist from Undyne, who backs off. They decide that they'll remain friends and leave for home.
 * Let them fall
 * Undyne dives down after Monster Kid to save them—she is badly hurt but refuses to rest. Kid tells Undyne that she was right about the human, who just stood there waiting for them to fall. This makes Kid hate the protagonist and all humans.
 * Run to Undyne
 * Undyne saves Monster Kid and is badly hurt. Kid tells Undyne that she was right about the human, who was too eager to fight her to bother saving them. This will also make Kid hate the protagonist and all humans.
 * Run away from Undyne.
 * Undyne helps Monster Kid up, who tells her that the protagonist was just going to get help from others.

True Pacifist Route

They are seen cheering the human onto victory as they face off against Flowey. In the epilogue, they say they don't think Undyne is that great anymore; and that they found themself a new idol. Monster Kid is also seen during the credits, attending Toriel's school.

Genocide Route
Despite being warned by Undyne that the protagonist has hurt a lot of people, Monster Kid approaches them anyway, in disbelief. The protagonist turns away, and then silently approaches Kid aggressively with a "weird expression". Kid will nervously stand their ground, and the protagonist eagerly enters a battle with them, declaring that they are "in [their] way". After subsequent resets, the protagonist simply attempts to trick the child into turning the other way, but fails and engages Kid. This encounter cannot be escaped from.
 * If Kid is attacked, Undyne takes the blow in their place. Kid escapes, whilst harboring a shocked expression. They are not seen again in rest of the game; it is assumed they evacuated with the others.
 * If Kid is spared, they say they knew the protagonist wasn't that bad and leave. This aborts the Genocide Route.

Flavor Text

 * Free EXP [Check]
 * Monster Kid quivers anxiously [Neutral]

Trivia

 * Monster Kid was designed by Magnolia Porter, who also designed Snowdrake, Ice Cap, and Jerry, and helped design Gyftrot. She has two webcomics, Bobwhite and Monster Pulse.
 * Monster Kid's design may have been inspired by the Pokémon Scraggy; both are small, yellow, bipedal lizard-like creatures with protruding teeth. While Scraggy may have arms, it has to perpetually use them to hold up its pelt—which is a lot like not having arms at all, just like Monster Kid.
 * Monster Kid is the only monster that cannot be defeated in battle.
 * In Waterfall, one can follow the conversation of someone and their sister via Echo Flowers. These may be Monster Kid and their sister.
 * When walking in the rain with Monster Kid without holding an umbrella, the protagonist's reflection will glitch and not animate correctly.
 * Going back to the room with the umbrella bin will make them say "Yo, I already looked, Undyne's not over here".