Arref and Ginger are talking about “sticky PCs” today — characters who really touch and affect other PCs by their very nature. It’s an excellent concept, and one I’ve used without having a good name for it for a while. In gaming, the easiest way for a PC to get screen time is to draw out the other PCs.
“Tell me your story — it sounds interesting.” The key is to enable screen time for other people, and get your screen time from the reflection, rather than trying to draw others into your story. Popular characters are those who facilitate someone else’s roleplay. The dynamic is most visible in large-cast games, like LARPs and MUDs, but I think it applies even in smaller face to face groups.