Halsin being very mindful of Astarion's "don't touch me"
Mindful enough that Astarion catches on to how deliberately he doesn't touch him. How even when Astarion has been downed in a fight, and Halsin has no time or ability to ask, he still says "I'm going to pick you up" before he does, or, "I need to lay hands on your wound to heal it"
So Astarion decides to fuck with him. Because he can. This is a man who was paying attention, who wanted to be so very respectful that Astarion can't help but turn it into a game, see how far he can push the druid.
Sitting too close, with no contact. Standing a little too close. Leaning over the large man's shoulder with his whole body to stare too-close at what he is whittling. It's easy to do, Astarion is a master of dextrous movement and seductive poses.
The first thing he learns is that Halsin is incredibly easy to get a reaction out of. "Heart on his sleeve" barely begins to cover it, the large druids heart rate picks up easily, he flushes, he telegraphs his responses with honest expressions. And yet still, he doesn't fall for the bait.
So Astarion starts touching him. Very, very innocently. Tugging at a loose thread on his shirt, flicking a leaf out of the druids hair. It's all fun and games, he thinks, with a goal of... With a goal of...
And one night, somehow, he's in Halsins' arms, warm and safe and listening to the sound of the big mans heartbeat thudding steadily while the fire burns low outside of his tent and he has no idea how he got here, but the game seems to have ended, somewhere along the way.