A/N This was a headcanon for Sean Cross :) Hope you enjoy :D
"Lucius, sit down!" Bellatrix snapped. Lucius stopped pacing and glared at her.
"This is my house, I can do as I please," he said and started pacing again. "We just have to wait for Cross with the details of Potter's whereabouts." At that moment, the front doors of Malfoy Manor burst open and Sean came running into the drawing room, red in the face and out of breath.
"Potter – is – back – at – Hogwarts," Sean gasped between breaths. "He – turned – up – in – the – Great – Hall." Bellatrix stood up and clapped her hands.
"Well, what are we waiting for?" she said with a malicious smile on her face. "Lucius, Narcissa, Sean, follow me!" She practically skipped out of the room, quickly followed with Lucius and Narcissa, hurrying to catch up with her. Sean had managed to get his breath back.
"Oh, don't worry," he said to himself. "I'm fine!" He sighed and walked quickly out of the room and followed Bellatrix, Narcissa and Lucius out of the front door.
"Okay," Bellatrix said. "Any moment, the Dark Lord will call us and we shall fight and bring glory to the family!"
"Err, I'm not related to you," Sean said. Bellatrix glared at him.
"All pureblood families are related somehow, Cross," she said.
"I know," he said. "But I'm not your sister or your brother-in-law." Lucius and Narcissa glared at him too. "I'm sorry," Sean said. "Wasting time is a – Ow!" His arm started to burn and he lifted his sleeve. The Dark Mark was black against his skin. Bellatrix cackled.
"It is time!" she shouted and Apparated. Lucius and Narcissa looked at each other, held hands and Apparated too.
"Okay, let's go," Sean said and Apparated to the boundaries of Hogwarts.