A little laugh at the ridiculousness, almost incredulity. Why would Gilgamesh say something so obvious? "I'm in love with her too."

There are more consequences to getting Dorian high than just making him suggestible.

He obeys the command, of course, follows his longing to its satiation, to Gilgamesh and his comforts and pleasures and company. Normally, Dorian is at least a little discrete in Hermione's company, but there is no discretion now in the arm he wraps around Gilgamesh's neck, in the kiss he takes from Gilgamesh's mouth. There is no sense of shame or self-awareness in the way he lets his body melt against his Servant's.

Also: there is no letting go of Hermione's hand. Resting most of himself against Gilgamesh, he turns his head to her, smiles with a serenity that suggests the loss of a few cognitive faculties. Even so, it is a smile full of love.

"Join us, Hermione. Please? The servants will bring us candied fruits and wonderful wine and we can lay in satin and talk of all the beautiful things in the world. We'll dress in flowing robes and sit under a canopy, and look on the sand that is our kingdom. Sands are always full of treasures, you know."

Not that Dorian has ever been ruler of a kingdom of sand.