Melanie is an NPC that can be found in-game, and will enter the elevator.

Melanie was teased for Regretevator as a hoax NPC, specifically to be killed by Folly, and was not planned to be in-game as an actual NPC; although she was still a canon character with potential lore to be revealed.[2] However, it seems at some point the plan for Melanie's inclusion changed; several more teasers and lore reveals continued to tease a potential return for her, and on November 29th, 2024, it was officially revealed and confirmed she would be added in-game.

Melanie was finally added to the game the next day on November 30th, 2024, after being repaired and revived by Mozelle.  

Melanie is an anxious, friendly person who seems to be very close with some of the NPCs. She is quite self-deprecating at times, such as stating "I'm not worth the trouble" when given certain items. She's nice to those who are nice to her, and can get quite anxious when Folly is mentioned. She also has a hatred for Folly after what she did to Melanie, which causes Melanie to make rude remarks about Folly when brought up in conversation. She has nicknames for certain NPCs such as Pilby (who she calls Pilbs.) She is also quite athletic, as she is the only NPC besides Wallter who can complete the Intense Obby, and she enjoys jumping. Mozelle calls her "hopscotch" as a nickname. She's helpful too, often offering to help others. In some instances, she asks if she could help Pilby get to their mother with the help of Mach. She also encourages Split when she mentions that she feels down while thinking about the future and Splitsville!. She also loves animals, as in one line of dialogue, she mentions wanting to protect the animals in PET CAPTURE DELUXE from "something."[3]

Melanie will enter the elevator from Mozelle's Humble Castle, as well as PET CAPTURE DELUXE (where she will also leave). In the latter floor, she will walk around and help players collect critters before entering. While in the elevator, she will occasionally force all players and elevator NPCs to jump as shown by an indicator above the player's items; this forced jump can happen in mid air, allowing players to "double jump" similar to using Fizz Up! This forced jump can sabotage players in floors like Toolbox Speedway, and help them in floors like WALL OF. She will also heal the player for around 5-10 health if showered with rose petals.

If Folly enters the elevator while Melanie is inside, she will become scared, her ears will lower, and she will start cowering and looking away. In this state, she will no longer force everyone to jump, nor will she heal the player if given rose petals. If Folly or MR are already in the elevator before she arrives, or the elevator is full, Melanie will not get in; if this happens in Mozelle's Humble Castle, she will take a seat at the dining table, and in PET CAPTURE DELUXE, she will wander off into the white void.}

I see Melanie as like a lighthearted anxious-like person, also with a robotic voice changer along with her, (because y'know, shes a tv!) Have fun, tho!

https://regretevator.fandom.com/wiki/Melanie - wiki!