Serenity

Serenity is a firefly formerly encased in a lump of amber that the Wayward Vagabond finds in the Skyship Base before it launches. Upon seeing the insect still alive and glowing in the amber, the Vagabond decides to use her to bring the Light of Democracy to Can Town. Later, the Vagabond releases her through use of the Appearifier and decides to name her something whimsical. The Vagabond actually has no idea if Serenity is a boy or a girl, or even if fireflies can be girls (which, in reality, they can't, as fireflies are the males of the species, while females are glowworms; however, fireflies in Homestuck may be different), but assumes the latter nonetheless.

She is intelligent enough to know that a countdown is rarely a good thing. She communicates via morse code and understands the passage of time. Her face seems to be stuck in the "blank stare" most of the time, which is used by many characters in MS Paint Adventures as well as the logo for the site.

A firefly that may have been Serenity appears in a lump of amber in the HS 3258 (flash game) at the start of Act 4.

Her namesake is the movie Serenity, which takes place after the final episode of the TV series Firefly. (Also the name of the spaceship Serenity in the TV series Firefly)