Would organizing fictional things (Such as characters in a novel or weapons in a video game) correlate to Si or Ni.

I've been using OP to find my personality type recently, I really like the system and I think it's simple and easy to use. I've become hung up on wether i'm an INFP (Jumper) or INFJ (Jumper. I know I use an introverted decider and introverted observer, I know this from both self analysis and what others have said about me. Any help with the question would be appreciated.