Perhaps the saddest creature of all,

Itsn't even a creature,

But instead, a simple line.

Parallel lines are perfect for each other. 

Oh, what a beautiful pair, the two.

They spend their whole lives side-by-side.

Yet not once do they ever meet.

Or rather, asymptotic curves.

They race towards each other with all their might.

But something startles them,

So they sharply turn and run away out of fright.

And then there are perpendicular lines.

Oh, what a tragic case.

The two lovers meet once,

Only to realize that the timeing is all wrong.

So the star-crossed lovers drift apart.

And not once do they ever meet again.