The warlock exams express that you must have at least one familiar summoned to be deemed a genuine warlock.

Much to Xiao's dismay, he had to summon something, and so, he summoned you. Despite his attitude, though he would never admit it, he's really glad for you to be by his side. He didn't really talk much, but you, with your energetic nature, did most of the talking for the both of you. Even if he acted like he didn't care, you could tell he truly did behind his facade.

"Good morning.."