Generally, most fandom activities fit into the “What do you like to do outside of work?” question. If you’ve listed in your application that you’re familiar with fanartist skills (Photoshop, metadata, paypal, etc.), answer if and when the interviewer brings it up.
Interview question: “What do you like to do outside of work?”
Answer along the lines of being part of an Internet community of [insert skill group. ie: artists, authors, etc] who met through interest in [insert your fandom here]. Discuss feedback, promos, networking, and the expansion of your personal skills. If you feel comfortable or are asked specifics, discuss trades, collabs, requests, commissions, performances, etc. Keep it safe for work. Unless exposure and familiarity with erotic media is important. Usually it is NOT.
Discuss specific troubles you have run into, your opinions on them, and how you solve them. If you can, tie in how those problems are more than fandom specific.
The most important reasons why you’re bringing up fandom in the first place is to make yourself stand out and to emphasize that you are dedicated.
Talk about canon to the level that you are asked. They ask who’s your favorite? Reply with who they are. If you’re asked why they’re your favorite, please do not respond with “because they’re an asshole.” Redirect back to positive traits that you share with the character. Emphasize how drawing them has helped you improve your artistic skill.
If you mentioned skills that relate to fandom in the application:
Explain them in your cover letter about how they relate to the job you’re applying for (PLEASE HAVE A COVER LETTER).
Have a portfolio! Have your name, contact info, and current, good pieces featured on it! Make sure your projects are complete and high resolution!
Explain them professionally. Focus on the skills. Focus on the tasks. Emphasize that this is a continuing thing.
Let the interviewer lead and discuss your skills and experience as it relates to the job you’re interviewing for.