Hello Jules, I recently discovered my little hen, Lemon-drop, is actually a roo, now named Lancelot. I've therefore been doing reading on introducing the little guy to a flock of all hens and came across this thread.
In reference to your question on what breed, his coloring is a lot like my Easter Egger. I was reading another post that said that one way to tell an Ameraucana from an Easter Egger is that Ameraucana do not have yellow legs, which leads me to believe he's an Easter Egger.
I hope everything worked out well with King Louie
