Lucius had been about to reassure Regulus, a boy who seemed to be unable to control his emotions when he had had a drink. Regulus clearly had a great deal on his mind and needed to be told that although his brother had failed to meet expectations, Regulus had surpassed everyone's. Whether or not those words would satisfy Regulus or even help him with his problem Lucius did not get a chance to find out.
He had just opened his mouth to shape the words when he heard Rabastan;s hurt reply, and then felt Rodolphus' smug satisfaction radiate towards him. "We'll talk about this later, Regulus." He murmured, unable to fathom exactly why Rabastan sounded the way he had. Regulus had distracted him from Rabastan and his task, but he had honestly not expected the boy to be so quick. "I guess I do owe you 20 galleons." He called to Rabastan, "I think that's probably going to be a record hard for anyone to beat, well done!" He said, looking to Rodolphus. "Help Regulus back up to the Common Room, don't let him have anything else to drink." He said, and his attention went straight back to Rabastan.
"The robes suit you. They'll look even better once you've got captain across the back." Lucius told him, clearing the distance between them, "We'll give the others a couple more moments, and then head back to the Common Room and announce the new team. I'm very proud of you, Rabastan."