I have seen them 'Fight',with each other,
for each other,
I have seen them 'to be there',for each other,
anytime anywhere,
I have seen them 'Help',each other,
'Love',each other,
I have seen them 'Care',for each other,
'Share',with each other,
&....
You are the one who can see them too,
as...
One of them is "Me" and the other can be "You".