Laures and Hilda are the main characters in the manga.

Laures is a demon-lord and wizard and has the vices that many men of power do- they will conquer what they desire for their own, or they will destroy it.
Then he meets Hilda, that is. Until Roderique appears, it seems that he simply uses her and comes off as one of those characters that you really despise and have no pity for. However, Laures seems willing to take a lot- if it is to protect Hilda, and eventually it becomes apparant that he actually cares for Hilda.
He kills a man who tries to seduce Hilda, and during the third volume of the manga, allows Berk to practice a little S&M on him "for the sake of Hilda's safety", even declaring war on Hilda's lover from before she lost her memory (Rod).
Despite his and Rod's rivalry, they are similarly haunted by the past, and fated to Hilda.

Hilda is a barrom dancer in a bar, and has lost her memory, the only thing she trusts is Laures.She doesn't know that Laures is in fact a demon, this is not revealed to her until Volume Three, after Zadei and Tetei capture her and Laures for Berk. Zadei tells her that her hunch is right, that the man she keeps calling "demon" really is one.
Hilda had two lovers fighting over her, Rodrique, from her past that she cannot remember, and Laures, the demon she loves but was betrayed by.

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Rod, who first appears immediately after Hilda begins to have doubts about Laures's character in the first mange volume, has a mark on his forehead that distinguishes him as the heir of the Sword of Azel, which allows him to unite with the sword, which is hidden in Hilda's body. Although the sword increases his power by tenfold, it also causes his soul to become darker.
Not only is he Laures's rival for Hilda's love, he is willing to destroy Laures for the methods which he used to secure Hilda's love.

It seems both he and Laures are fated to be Hilda's lover, and yet both know that Hilda prefers Laures, even after it is revealed that he is the one who erased her memories in order to keep her for himself. Rod is upset that she will not acknowledge his affections, and can often be seen in a sort of "broody" mood during the manga.