the heartagram as its called is the symbol for HIM... it is sort of the ying-yang symbol as the lead singer of Him, Ville Valo has at one time described it... It means love and good... Its around a lot more now as the band is more well known and its a symbol to show your pride and acceptance and support of the group.
it was invented by Ville Valo of HIM...
I don't want to look back;I just want to start again;Somebody save me--- Pop Evil: Broken and Betrayed
I want justice I want you overthrown;I want courage I want to stand alone;I want your arrogance and I want your pain;I want your everything and I want you dead--- Rev Theory: Justice