Ulquiorra listened to Zexion speak with his eyes closed. The information was useful, not least the fact that the man, a scientist, and that was part of the stated reason for being so keen to bring him into the fold, was of a personality to require appeasing, but also the tension between him and Marluxia.

Ulquiorra wasn't present to appease anyone. He was here to guard Zexion, and potentially subdue a reluctant acquisition. It would be down to Neliel and Zexion to appeal to the man's ego and entice him to join them willingly.

If nothing else, the fact that Nel had nearly killed the fire elemental in their encounter might hold some encouragement, if he despised the fire elemental as much as he despised Marluxia.

Not knowing Lumi, however, made Lumi, who felt powerful, and who seemed as loyal to Marluxia as Ulquiorra seemed to Aizen (Appearances could be deceptive a voice whispered, internally, and Ulquiorra shut it down), might deter Vexen from joining. Lumi was too much of an unknown quantity, and the fact that Marluxia kept him close enough to bring him on a mission such as this despite that possibility only made it worse.

"Lumi and Marluxia should not have attended," he said, quietly.