You need to rest before meeting the Dreamer, so that Lae'zel can inspect you for tentacles and say it's odd how we're not showing symptoms yet. Then talk to Astarion and he'll make jokes about it.
Important to know that just because a companion doesn't have an exclamation mark above them, doesn't mean they have nothing unique to say. I always talk to everyone each time I take a rest as they always have something awesome to say ^^
