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Monkey changed a lot since we last met him.
Heck no, he didn't "grow up". Tricksters never do.
But he got stronger, older, smarter, and more powerful. He had a trip to Heaven and back; on the former occasion he was invited, on the latter he left because he didn't like the job he got up there. So he went home to the (now immortal) monkey folk, and promised them a new home: Heaven.
Of course, the Jade Emperor and his Court can't let that happen (imagine Monkey ruling the Heavens...). So they send an army to subdue the Monkey King.
Their first troops and general are beaten in no time at all, and they go running back to the camp. And now that Heaven's army knows just how incredibly powerful the Handsome Monkey King is...
... they send a child.
This is one of my ever favorite parts of the whole story. If not the favorite.
The child is called Nezha or Na Zha, most commonly known to us by his Japanese name, Nataku (thank the anime genre for that). He is a fire deity, an enfant terrible, a child trickster himself. As the third son of Li Jing, one of the Four Heavenly Kings, he accompanies his father to the campaign against the Monkey Demon. He is very young, and looks innocent enough; when he appears in front of Old Sun, nobody runs or cowers.
Well, they should.
Tricksters like children. Also, tricksters are like children. This is why sending a kid against the feared demon is such a very nice touch to the whole story. Monkey greets the boy who shows up out of nowhere with kindness and a pat on the head.
And then the cute little boy turns into a giant warrior with three heads and six arms, holding deadly weapons.
Am I the only one here who's thinking 'I'd like to see Sun Wukong's face now'?
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And thus begins the most awesome trickster vs. trickster duel in the world of Journey to the West. It is detailed in a long poem, in vivid pictures, and reading it you can imagine the full-out battle that rages agains these two between Heaven and Earth. Magic, subterfuge, tricks, shapeshifting, weapons against weapons.
Something tells me Monkey is having the time of his life here.
Among all the demons he'll fight later, along the journey, none was as equal an opponent to him as the Prince.
Also, he'd be in for some major @ss-kicking from a six-year-old if he wouldn't have the nasty habit of cheating. Which is as natural a trickster art as any, but looks like Prince Nataku hasn't gotten the hang of it yet...
(No spoliers now ;) Read the book!)
All in all, Nezha remains one of my favorite 'minor characters' in this story.
One word: EPIC.