Do you think why the music is so sad, is because it's Dirk remembering all the adventures he had with Jake on his planet? Could also explain the swirling red mass of a storm in Dirks chest/heart... could it be the conflicting feelings of the separation from the one person he truly loved? Poor sweet shit wrecking prince...
I kind of feel like dirk is just thinking of all of the mistakes hes done, how he could have been a better person, and what made him /him/. The way others flaws molded him when he could have molded himself into a much better person, only to become consumed by them??? Dunno
It is a fan made song for the webcomic called Homestuck which you can read over here (but if you were to do so please mind that it is a fairly long read and you usually have to read up to Act 4 before you can decide whether you want to finish it or not): www.mspaintadventures.com/