Motherhood. You're suddenly the expert on this little life... And yet this person is a complete stranger that you only met a matter of weeks ago. You practically have to read this individual's mind, yet you've never had a conversation with them, and you won't for months and months.
But slowly, you develop an understanding. There are things this little person likes, and dislikes, understands, and is amazed by, is concerned about, and is learning about... And you get to influence their interaction with the whole world.