TW: mentions of favoritism and child abuse ahead!
Amber was born in wrath to Comet and Selene with the latter in childbirth. Due to this and the fact that Amber looked so much like her late mother, Comet resented Amber. Amber grew up where she was abused by her father and older brother Titan, who her father favored. Amber would end up running away, making her way to the Pride Ring.
Not wanting to be brought back or being placed into a pound, Amber began living in the streets. During her time on the streets, Amber took Vesper, another young hellhound living on the streets. Amber is the more aggressive of the two, putting on a very combative and aggressive front in order to protect herself and Vesper.
When Vesper got sick, Amber began breaking into various houses and shoplifting various stores for food and medicine for the sick hellhound. One night, she ended up breaking into a goetia manor for some food. There, she was caught by Marsha and Octavia, who ended up adopting both her and Vesper.
Amber and Vesper began to live with Marsha and Octavia where they were integrated into their large family. Aside her new immediate family, Amber also spent a lot of time with her cousins who lived at the Hazbin Hotel. This is where she would meet Josie, the child of a pair of sinners who lived at the hotel. Josie became Amber's first real friend outside of Vesper. This is also where she came to idolize her aunt Marceline, who got her into music (especially punk rock).
Much like Elise II, Amber was often "dehumanized" by higher class demons outside of their family due to being a hellhound adopted by demon royalty. Although, her experience wasn't as bad as Elise II's due to Elise II being there for Amber.
Regardless, by the time she was a teenager, Amber had learned how to express her feelings through songs and in an effort to get some of her pent up anger out, began putting how she felt about all of her hardships (her bio family, being homeless, the dehumanization) into song. During high school, Amber formed a band with Josie alongside some of their friends which they still peform in to this day.