The String Boy

I once knew a boy    
Made completely of string    
I didn't see  
His unraveling    
So I never said a thing    
For he smiled      
And    
Laughed    
And    
Appeared just fine  
[Most of the time]  
We just took     
Careful steps    
To avoid    
His unwind    
Yet    
Day after day    
More string he would lay    
But    
The boy never acted    
In an alarming way  
So no one ever pulled    
On his lifeline       
He then kept going    
Until  
We ran out of time    
And he    
Out of twine