the place i belong (is here with you)

Claude balked, “Wait a minute, you don’t seriously mean to tell us you’ve been here all this time, do you?”

Again, Cyril seemed surprised at the question. He blinked, answering in a matter-of-fact tone, “Of course I have. Where else would I go?”

From Cyril, the question was not an accusation or a plea for pity; it was a statement of fact. Garreg Mach Monastery might as well have been the whole world as far as he was concerned, and Rhea the sun it revolved around. Of course it would never have occurred to him to go elsewhere, to do something other than keep trying to fulfill his duty to Rhea and take care of the monastery.

~~

Or the one in which Claude and Byleth adopt Cyril (basically).