Thing I learned: Parker-style refills, which I previously noted their ubiquity, is actually an International Standard Organization (ISO) standard: ISO 12757. Going down this wormhole, I also found a very handy guide to pen refills.
At Claire’s, doing the father-of-a-daughter thing. She’s patient with me at bike and office supply stores*, so it’s only fair.
*Actually, my daughter is an office supply geek herself. She’s usually quite happy to go with me.