It seems that Jack is the main character. He is the one with the task of slaying the giants. King Erik may be an important secondary character, but Jack is the one who drives the action forward in terms of the giant - slaying part of the story.
Well, 'Jack the Giant Slayer' is a well - known story. Jack is a brave young man who manages to slay giants. I'm not sure who 'King Erik' is in this context though. Maybe he could be a king that Jack helps or is related to in some way during his adventures against the giants.
In the 'the lyle and erik menendez story', Lyle and Erik Menendez are brothers. They are known for their heinous act of killing their parents. Their case got a lot of media attention and raised many questions about family and crime.
Since it's a fanfiction, Erik Lehsner could be an original character created by the author. He might be a fictional being with certain special traits or powers that are important to the story. Maybe he's a supernatural entity, like a vampire or a wizard, which would add an interesting dynamic to his relationship with a human.
Erik is likely not based on a true story. Many such characters are invented to entertain or convey certain themes and messages, rather than being rooted in actual happenings.
It can start with conflict. Raoul is the 'good guy' and Erik is seen as the 'bad guy' at first. But as the story progresses, they could find common ground. For example, their shared love for Christine could be the starting point. They could have a conversation where they both admit their feelings for her and realize that they don't have to be enemies.
In fanfiction, Erik's possessiveness of Charles might be an exaggeration of his character trait. He may have a sense of ownership over Charles due to their shared experiences, like founding the X - Men together. His possessive nature could also be a way to show his intense love or loyalty towards Charles, in a rather extreme way. He might think that Charles belongs with him more than with anyone else, whether it's in their mutant - related activities or in their personal relationship.