"Not only that, but Merlin is here, as well. The Merlin. Which I find utterly mind-blowing." Given his fascination with Arthurian legends, Oliver would understand why Percy thought that way.
Percy had to calculate for a moment before answering. "Fred is 20 years old and George is 27. Which makes it significantly easier to tell the two apart, now. But it's... good to have Fred alive here, despite their prankish natures."