Maybe it was his extracurricular activities, or maybe it was his status as a mage, but Emrys didn't think he could deal with the cops alone.
The Enchanter sat across the street from the station in his 68 GTO, music from an old cassette was muffled but still escaping the vehicle. Inside Emrys had his phone out watching old news footage, memorizing the faces and the place he needed to postcog. He was ready to get this over with, but something told him he wasn't just going to waltz in mutter linguistic jibberish and space out on the cops for a few minutes without raising eyebrows.
That's what Arthur was going to be there to cover.