When Locke first showed up at Figaro Castle, Edgar was convinced that he was an Imperial spy. Surely someone that young (though he supposed he was only a few years younger than himself) and... roguish couldn't possibly be a contact for the Returners. He'd never met anyone else from the Returners, had no one to compare him to. Did they really expect him to believe him with only his word to go on?
When Locke proved himself a clever wit at his interrogation, cleverly disguised, Edgar had thought, as dinner, he gained his respect almost immediately. He'd peeled back the veneer of civility and answered every one of Edgar's questions with as absolute candor that impressed the young king. He drank a bit too much wine, but didn't seem the worse for it, and swore a bit too much, but other than that, he could have been any courtier at his court, and yet his honesty made all of them seem like nothing more than colorful, fluttering things, insubstantial as air.
When he caught Locke deftly manipulating a coin with thin, agile fingers, he couldn't resist watching a moment longer than was strictly necessary. Surely Locke had seen, but he said nothing. When Locke caught him dallying in an alcove that night with a pageboy instead of a chambermaid, he equally said nothing, just smiled a strange little smile, and walked away.
When Locke showed up at his door the next night with two bottles of red wine, a bottle of salve and a crooked grin, displaying the latter two as prominently as the former, and, later, made himself as at home in his silk sheets as Edgar himself was-- that was when he decided this was the start of a delightful friendship.
It was nice to be right about some things.