I've used 4 online spellcheckers, and only one of them marked it as an error. There are also lots of examples of "I want you kneel" phrase in the internet. I think "want" can act like a modal verb in this context.
I need it for a song, so the meter matters. You know, the grammar may be "flexible" in songs and poems, but to what extent?
George Yury spellcheckers Spelling is not grammar. Every word in "They want you kneel" is correctly spelled, but the sentence is not grammatically correct. George Yury There are also lots of examples of "I want you kneel" phrase in the internet.
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George Yuryspellcheckers
Spelling is not grammar. Every word in "They want you kneel" is correctly spelled, but the sentence is not grammatically correct.
George YuryThere are also lots of examples of "I want you kneel" phrase in the internet.
Not everyone who writes on the internet is an English speaker, so there
George YuryI need it for a song, so the meter matters.
There are many ways to rephrase a line...
I want you down
Down, on your knees
Pleading with tears
etc. etc.