Rose Lalonde is one of the principle characters of Homestuck, being introduced in Act I. She is the first female character introduced in Homestuck, being the Instant Messeger friend of the first protagonist, John Egbert. Like Dave Strider, she is a few months older and a lot more sophisticated than John. In terms of easily describable youth culture, while John is an everykid and Dave a type of hipster, Rose is a goth, fond of dark colors and imagery, and writing and speaking in a pedantic, sarcastic and pretentious style. While John lives in a typical suburban situation, and Dave has a slightly odder but still plausible family situation, Rose's living situation is one of the first signs of Homestuck breaking into science fiction territory. She lives alone with her reclusive and inebriated mother in a laboratory in upstate New York, which brings her close to the catastrophe that starts the main arc of Homestuck.
Despite its heavy and convoluted plot, Homestuck is primarily a character and dialogue driven story, and Rose's role in that is paramount. Among the four characters first introduced, Rose is by far the most sophisticated, and her exasperated dialog dealing with the exploits of her less mature acquaintances provide some of the most humorous moments of the story. As the story progresses, more serious issues of Rose are explored, mostly dealing with her conflict with her alcoholic mother, her own issues with alcohol, and her desire to find a sense of purpose. Within the mythological framework of Homestuck, Rose is affiliated with the aspect of Light, and throughout the story, it is said that she will breed lilacs out of the dead ground. It is suggested that Rose will have a role in enlightening those around her, and providing meaning to a story full of constantly shifting plots, locations and timelines. This role is left as an ellipses, at least on the surface. Whether this was deliberate, whether the purpose of Rose Lalonde's actions were left hidden in the million words of Homestuck, whether it was an example of writer fatigue as Homestuck finished its seventh year, or if I am just missing the correct viewpoint to understand Rose.