Loki is the king of the outcasts
That's Oden.
Loki should be his opposite.
Harold wanted to accept any type of creature in Elbaf (like Big Meme's kingdom), whereas Loki, "destroyer of the world", only thinks the worthy ones (a la Valhalla) should be allowed in.
When Harold rebuffed Loki's philosophy, Loki tried to ally himself with his father's analog (Big Meme), only to destroy his father's legacy and, at a later time, turncoat and betray Big Meme, too. But, alas, Lola screwed up his plans, and then Shanks ganged up on him and had him imprisoned.
Now, a new character (Luffy) who accepts anybody, in spite of lineage and power level, is here to help Loki. Luffy represents everything Loki dislikes: his father's philosophy and Shanks' protégée status. So, once he tricks Luffy into freeing him, Loki will go berserk and set everything afire.