Claude is distinctly apathetic; he speaks and acts virtually without emotion. He does not respond to direct taunts such as Alois Trancy undoing his buttons moments after Claude fixed them. Claude's personality drastically changes after he tastes Ciel Phantomhive's blood. He begins to covet Ciel's soul and becomes erratic and bizarre; he would dance and make doilies.[citation needed] Having developed a strange obsession with Ciel's soul, Claude is determined to obtain it at any cost.

How Claude acts in the S2 Ep7:

When the battle resumes, Claude pulls an ancient demonic sword, "Laevateinn" out of Hannah's mouth and challenges Sebastian to a duel. He manages to corner him in a mass of spider threads, sturdy enough to cut through steel. But as it seems Claude has the upper hand, both butlers hear sounds in the mansion and rush in to see Ciel confronting Alois. Claude stops Ciel before he can deliver the death blow by grabbing his sword. As Ciel flails, he slaps Claude and leaves a trail of his own blood on Claude's cheek. Tasting Ciel's blood leaves Claude in a stunned state until Sebastian calls his attention. Claude ignores his wounded master, who is pleading for his help, continuing instead to taste and analyze Ciel's blood. This suggests the abandonment of the contract.