I just really like how much Weyoun self-soothes. Everyone has some self-soothing behavior they do occasionally, and some people do it more than others. Weyoun does it in literally EVERY scene he's in, and I find that fascinating.
He presents himself as confident, light, unflappably optimistic... but if you watch his hands you can see the anxiety he hides.
In a tense moment, he'll have the biggest smile:
but behind his back:
He doesn't let himself touch his face or bounce his legs. That would be too obvious. But he can't stop himself from holding his own hands, squeezing them, stroking them... little things to give himself comfort.
Crossed arms or one arm across the chest can be an inconspicuous self hug. Good for moments when you're dealing with stressful people.
Your God is displeased with you? No one else is going to comfort you.
And that's the thing, really. No one else ever comforts him, or any Vorta. They are lab-grown servants. They live as attendants to their Gods, or diplomats among other species. They don't get to have actual friends, or partners, or family.
Vorta are barely ever touched from the moment they are activated. So of course they are going to rely on themselves to fulfill that need. Of course Weyoun is constantly self-soothing. It's all he has.
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Final note: please watch both Weyoun and Damar make subconscious fists when they talk to each other.
They hate each other so much.