While Rheaga appears to be a monster he will not attack you unless you attack him first.
You can choose to kill him or not.
If you choose to kill him you can loot his head from his corpse and return that to the NPC.
If choose not to kill him you can take a Letter off the ground near him and return that to the NPC.
Both options give the same experience reward but different titles.
Lore & Dialog
Hea Rheaga tells you, "Greetings, human. Have you come to slay me? I have divined, through my vast intelligence and penetrating senses, that a human named Nomea in your shantytown of Qalaba'r wishes me dead. Simply because I am a failed experiment of the meddler Aerbax. I can assure you that I pose no threat."
Hea Rheaga tells you, "I have no desire to meet, let alone unite or enslave, my brethren. Nor do I care to wage any kind of war, by arms, sorcery, or guile, against humankind. I have studied enough to know that no good can come of treating with your people."
Hea Rheaga tells you, "If you would slay me, be done with it now. I can assure you, death neither fascinates nor terrifies me. I am not particularly attached to the life I have been given."
Hea Rheaga tells you, "If you would spare me, merely pick up the note you see before me, and deliver it to Nomea. I am convinced it will convince Nomea of my benign intent."
Hea Rheaga tells you, "Be warned, I will fight back if attacked. I am not completely apathetic, after all. I do possess some survival instinct."
Hea Rheaga says, "Is there anyone at all like me? Anyone as unfortunate as me?"
Death Message:
Hea Rheaga says, "Oh dear... It looks like death is just as boring as the rest of this uninspiring existence..."
Head of Rheaga 