Line of Demarcation

My two daughters,
Each territorial creatures
And sworn enemies,
Staked out
Their respective spots
At opposite ends
Of the back seat
Of the car.
Like two snarling tigers
They each rode,
Ready to hit or kick the other
Should she dare
Cross over the imaginary
Line of demarcation.
If it wasn’t that,
Then it would be
The ritual complaint
That the other one
Was looking at her,
A most grievous wrong
You can be sure!
They nearly drove us nuts
With their bellicose bickering,
And I chuckle to think
That they will someday
Have kids of their own
To give them back
A dose of their own medicine!