If he'd been in the Muggle world, Theo might have been considered something of a geek. In the Wizarding World he was a complete geek for spellcasting and his Ravenclaw sympathies alone meant that he completely understood what Dominic meant by making it work 'fun'.
He was absorbed in Dominic's tales of how the journals worked, intrigued as to where the problems had been. "The Cursebreakers are trying to break the journals system?" he queried, unsure what that was all about but feeling defensive on both his journal and Dominic's behalf.