Niffty/History

Past
Niffty was born sometime around the late 1920s/early-mid 1930s as a human. She died sometime in the 1950s at the relatively young age of 22 years old.

During her time in Hell, she met Alastor and became acquainted with him. Then a little while later, she met Husk, and he also joined her in working with Alastor. What sort of partnership the two had is unknown, although she can be seen in a flashback as one of his allies.

Hazbin Hotel pilot
When Alastor decided to help Charlie with her hotel, he summons Niffty to be the maid of the hotel. Once coming to the hotel, she noticed how filthy the hotel was and began cleaning as quickly as possible. This continues during Alastor's Reprise, quickly picking up a skull that had been kicked by the Radio Demon. When Sir Pentious blows up one of the walls with his airship, Niffty is hit by some debris but presumably cleans it before joining the others outside to gleefully watch Alastor destroy it.