In the Book of Urizen, to the great dismay of the Eternals, Los and Enitharmon had managed to bring about offspring (their further offspring is the subject for another post).
Their first born, Orc, was the apple of his mother's eye. Her husband got tired of that and took firm measures:
Book of Urizen, Plate 19.48-9, (E 79):
"The Eternals, closed the tent
They beat down the stakes the cords
Stretch'd for a work of eternity;"
Book of Urizen, Plate 20:1-26, (Erdman 80):
"No more Los beheld Eternity.
In his hands he siez'd the infant
He bathed him in springs of sorrow
He gave him to Enitharmon. "
Book of Urizen; (E 80):
"They named the child Orc, he grew
Fed with milk of Enitharmon
Los awoke her; O sorrow & pain!
A tight'ning girdle grew,
Around his bosom. In sobbings
He burst the girdle in twain,
But still another girdle
Opressd his bosom, In sobbings
Again he burst it. Again
Another girdle succeeds
The girdle was form'd by day;
By night was burst in twain.
These falling down on the rock
Into an iron Chain
In each other link by link lock'd
They took Orc to the top of a mountain.
O how Enitharmon wept!
They chain'd his young limbs to the rock
With the Chain of Jealousy
Beneath Urizens deathful shadow"
Among other things Blake gives us here a pretty vivid, not to say lurid, description of one of the common fates of our young people marrying in haste. He also plots the course of jealousy, how the mind-forg'd manacles take possession of us; he called it the Chain of Jealousy, cursing alike in this case father and son. In Gates of Paradise he further explicated that theme:
"11 In Aged Ignorance profound,
Holy and cold, I clipp'd the wings
Of all sublunary things,
12. And in depths of my dungeons
Closed the Father and the Sons."
In the course of his career Blake used Orc for higher and better purposes: Red Orc introduced the American Revolution (I wonder if Tom Paine had read hair.) If you wanted to study Orc extensively, you could read all 114 of its occurrences.