"Did you read that off my name badge?" Eric retorted. He received nothing but a bad 'vibe' from Rodolphus, and Eric was not one to necessarily think 'vibes' were very reliable. The wizard certainly intrigued him, however, and Eric found it irresistible to not take advantage of the situation.
After all, why would someone attack him? Eric was not one worth anyone else's time. If Death Eaters and dark wizards insisted he proclaim his loyalties to them, Eric likely would have laughed. Sure, Eric was smart, but he was certainly not in any position of power. He just knew things, saw things. Eric hated dark wizards and did not trust them, but he was not above selling his loyalties if the offer was good enough.
"No," he corrected, "this is a perk of the job. My job is to make sure you're not trespassing. I'm a watchwizard, Mister Lestrange, so my job is to watch you, whether or not you like it."