Theo gave a short half-laugh at Ernie's commentary on his drawings because really, he hadn't seen them. The smile lingered though and it was aimed at Ernie even when he lifted his glass and sipped at his coke. He let the shadow of the topic of father's slip away to the little box where it could stay and paid attention to a much more pleasing topic - Ernie.
He shrugged good naturedly because it could do - he'd seen the abstract art of some painters and had actually enjoyed it more than landscapes and portraits - but it seemed that Ernie's passions lay elsewhere. "I like the waltz." he mentioned, having been trained in most of the formal sociable dances (and some of the more obscure, just in case) during his pre-Hogwarts education. "Or at least, I like hearing it played and watching it peformed. I'm not a dancer." he disclaimered quickly.
"Did you like Herbology?" he was curious to know. "What kind of plants do you like? What kind of roses does- do you have?" he asked, skipping again over family, always family. He withdrew back into studying his glass a little, irritated at himself but not showing that on the outside. "Well, thestrals, as you know." he hadn't seen any in a while though. "I like researching obscure magic. Oh, I like languages." he added, recalling that this wasn't something everyone else appreciated.