Them.

Someone that was once a stranger,
Is now the one person you know like the back of your hand.
Someone you once had no emotional attachment to,
Now has the power to completely pull the rug out from beneath you.
Someone you never used to spend time with,
Now takes up most of your day.
Someone you never thought you'd love,
Now owns your entire heart.
Someone you once lived without,
Is now the one person you need to survive.