>>52535104I think people in the center are there because, according to Cover, they had the biggest initial impact on their branches. Sora started it all, and without her there would be no Hololive. Moona was one of the most popular ID members who prevailed and grew, and as a result of that, ID3 happened. Gura's popularity during her peak was only rivaled by Pekora, and she put EN vtubers on the display, and broke all sorts of Cover and vtuber records. Besides all that, she's cute, so expect Cover to plaster her everywhere until she graduates, or until EN kouhai overtakes her, but I don't see that happening anytime soon. If it weren't for those 3, you'd probably see Risu, Miko and Mori instead.
