Much to Ciel's chagrin, Alouette had been rather wary of the warrior-type Reploid, preferring to let Ciel talk for her when the need arose. Thus, Ciel devised a way to break the ice, in the form of a game of hide and seek.
While Zero was an excellent warrior, properly hiding from Alouette and Ciel was apparently somewhat beyond him. At least he tried. Upon being told the objective of said game, he had taken to the "hiding" aspect with an almost frenzied desperation, especially so whenever Ciel was "it." Much to Ciel's amusement, being found by Alouette was apparently the ultimate defeat, as he had taken to making a show of being overly mopey until the young Reploid girl offered him some sort of consolation.
To his credit, he was surprisingly… flexible. Both Alouette and Ciel had a rather easy time figuring out where he was hiding, but always in the places you would not expect to find a Reploid.
While they were clever and all-around unusual, not being able to fit properly in them was what had been his undoing. The hard part was figuring out how he had even managed to get into the air ducts of the Base, or between Ciel's bed and the adjacent wall, along with numerous other unorthodox hiding places. Ciel, incidentally, spent the majority of her time whilst hiding from either Zero or Alouette attempting to deduce how he had managed to even get to his hiding spots.
Being "it" himself was an entirely different matter, it seemed. He always managed to find Ciel first, and then take his time searching for Alouette and purposefully overlook her hiding places in a rather obvious(and apparently much appreciated) attempt to humor the child, often accompanied by his own quiet effort at praise.
Nevertheless, what had been intended as a way to encourage proper interaction between the two Reploids had proven to do just that, with both earning a friend in the process.