After her debut album Fishmonger garnered attention from high-profile musicians in March 2021, Underscores began working on its companion.

Boneyard AKA Fearmonger is a hyperpop and pop-punk EP that range from acoustic ballads to electronic dance music.

Similarly, the American musician Brakence was recommended Underscores' 2019 extended play (EP), We Never Got Strawberry Cake, by a friend; he said he was "blown away" and "had never heard anything like it before".

[1][5] Boneyard AKA Fearmonger is a hyperpop and pop-punk EP that blends electronic beats with fuzzy guitars and manipulated vocals.

[5] The lyrics in the EP are introspective and deal with themes of "anxiety, existence and generational apathy", according to Ali Shutler of NME.

[1] "Girls and Boys" is reminiscent of 3OH!3's music, which combines crunk and pop;[11] lyrically, the track reverses the perspective of voyeuristic songs regarding sexual minorities.

[10] A loud and fast-paced track, its opening line was called a "memorable snub" by Leight: "My doctor asked me if you were to die for / But you're not even someone I would lie for".

[5] Gabby Start makes an appearance on "Loansharks",[13] a track aimed to bring dubstep's energy back to pop music.

[5] The track was compared to the music of Jimmy Eat World by The Fader's Jordan Darville; the song was written about a celebrity that Underscores based her "whole personality off of".

[10] Darville thought Underscore embraced a pop-punk influence on the EP more effectively and prominently than is usual for hyperpop artists.

[11] Writing about the track "Girls and Boys", Ellie Robinson of The Music called it "one of the best songs ever written about the way trans women are often fetishised by straight men".