Kids

Quite sturdy and robust, XY is just used to the rough play by the brothers. The brothers though adore her and always carry her around. They put her on a chair where she will then climb up to the table, or put her on the bed, or stairs. They take her as their pillow and sleep on her. She is happy and excited when she sees them around. And since she only crawls and disturbs their play so she is called "crab". she loves food and always calls out to the brothers when they are eating. The brothers generously share theirs but only get scolded by the father for feeding the little sister junks. 

The brothers on the other hand, have been on a serious talk with the father and Google Assistant every night. This thing sounds like their girlfriend that they ask her many unrelated questions such as is iPhone good. Most of the times, she doesn't get what the kids ask. So she is scolded for being inefficient. The boys and the father have a bro thing that I cannot blend in. But oh well.....