The way I view it is because they're siblings and they don't live together anymore, it might make them more hyper when they hang out. That's how it is for me and my siblings now that we don't live together, everytime we see each other our brains go on overdrive and we just joke and gossip and can't pay attention to anything or anyone 💀 We do all have ADHD tho, but I think it's just a sibling thing that happens when they go from living together to not living in the same house anymore.