"Oh." A house elf. "I didn't realize you had a house elf," he said quietly. "I suppose that would make sense. Mum and Dad are muggles, so they wouldn't have a house elf...and yeah." He smiled at him a little. "Maybe you could learn from my mum. She's really good at teaching cooking. She would not get offended." His face fell. "But I guess you can't right now."
Colin just stared at Zach quietly for a moment. "Why?" It didn't make sense to just be rude for no reason. There had to be some reason. Even if it was a little reason. Colin could never be rude to people unless they were rude to him first...or Death Eaters. Even then, it was perhaps more intelligent not to say something rude if he ran into one of them.
Colin smiled a little, curling up and getting comfortable in Zach's lap. He would move if he was asked, but until then, he was claiming Zach's lap as his own. "I don't think you can help whether or not something collects dust," he said, laughing a little. "There is dust all over the place."