It's the first revel Eris' children are attending. The younglings begin socialising without the parents being there. What are his greatest fears with respect to both his children?
hooooo boy okay i will say — his children are never without some form of supervision. probably like ever in their lives, even when they think they are, even when they’re older and can fend for themselves. eris is near-cripplingly paranoid and has plenty of reason to be. (even if he at some point somehow got to a place in his life where he didn’t have reason to be paranoid, he would never be able to stifle those instincts.) so at the very least, the twins would have personal guards nearby, prepared to sacrifice their lives and/or slaughter an entire room full of younglings if the need arose lolol
but this could still be the first time eris doesn’t have eyes on them himself at a revel! and that would make him real antsy. you will never have seen someone better at pantomiming an engaged conversationalist than eris holding court with the snakes of his nobility while their viperous little hatchlings are slithering about his children.
i feel like at this age — i’m picturing them as the fae equivalent of pre-teens maybe? — his fears are pretty much the same for both. he’s concerned that they won’t be able to hold their own if (when) the conversation turns nasty — or not even that they can’t hold their own but that whatever is said will nestle into their minds and take root. (be that something as minor as adolescent insecurities or as major as turning against him.) there’s also the concern of these other younglings being tasked by their parents with wooing his children, making inroads for betrothals, taking advantage of their youth, etc.
more than anything though, i think a quiet fear of eris’s is that — they’ll finally begin to recognize how awful of a life it is to be the child of a high lord. they’ll see all these younglings who already know each other, who have already been to galas and banquets and functions together, who have formed friendships and relationships, and they’ll realize that they can never be a part of it. not really. they’ll realize that the children they meet and the adults they’ll become don’t want to know them, only gain the prestige of being around the heir or the daughter of autumn. he’s afraid they’ll start to feel in that moment how he’s felt his whole life, and he’s so, so afraid that nothing he does can prevent that.