I watched this movie once when I was definitely too young to really understand what the hell was going on
The movie was mostly about these two boys who went to what I think was a british school. I can't remember much about the beginning of the movie, but basically the MC was like, average if a bit of a loner, and the second boy was like, an edgy loner, and sort of obsessed with ancient societies and brotherhoods (think freemasons and templars), and unknown to the first boy, their fathers are in one of these (nothing mystical about it, I think the movie didn't say they were freemasons, but certainly implied it).
IIRC, MC's father was higher up than second boy's father, so second boy was like, obsessed with having the MC be his 'lord', as if second boy was a knight. I think at some point he compared himself to a Jack of Spades, the card, though I believe he also referred to the Spades suit as 'Pike'.
Also, while all this is going on, MC has a crush on a girl from school, who was part of drama club, I think. Halfway through the movie, the girl dies in an accident which is implied to be second boy's doing. I think there's a scene of both boys breaking into the morgue to see the corpse.
Then I don't remember the sequence of events, but the MC manages to get the second boy arrested for the girl's death after some falling out, and the movie ends with MC on a train with a bag that's implied to have the girl's skull (which is a parallel to one of the stories second boy told MC about one of those ancient brotherhoods).
Every now and then I remember this movie, but haven't been able to identify it yet