What is the work?
Amon Amarth is a Melodic Death Metal band situated at Tumba in 1988. A majority of their songs deal with Vikings and Norse Mythology.
Who is the candidate?
From their second album Versus the World comes the protagonist of the song "Where Silent Gods Stand Guard." In it, the Viking was an undead, vampiric fighter who decapitated ten men, relishing at how they begged for their pathetic lives. He talks about taking their souls and ate their "steaming eyes" and drank their blood, making them his eternal slaves. He is also revealed to have done the same to one thousand other victims, mounting their heads on his shrine as he calls "macabre trophies from his prey."
He then ends the song by boasting that he would enter the gates of Valhalla when he died in battle (as it was believed that if they died without honor, they'd end up in the other place).
Freudian Excuse? Mitigating factors?
None. His defining trait is that he is a severe case of a BloodKnight who prides himself in slaughtering his enemies. He outright calls himself a "wolf in human shape" and a "predator with flaming rage"
I wipe the blood from my sword
And slide it in my belt
This is the sweetest of rewards
The best rush I have felt
Ten men are dead by my feet
I smell their steaming blood
And I smile, cause it makes me
Makes me feel so good!
The album primarily focuses on the events of Ragnarok and gods like Loki do play some parts in the songs. With the protagonist from this song, he is nowhere near the scale that the Norse gods are, but he has a niche where he kills others and eats their eyes and drink their blood so he could make them his eternal servants, barring them from the afterlife. And he had done this thousands of times given how long he had been operating.
I'll leave this for you guys to decide.