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He held the rank of Jedi, but the Jedi Council were jealous and didn’t give Anakin what he deserved.
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He saw visions of his wife dying and was willing to do anything to save her, yes, including killing kids. This isn’t evil; this is true love.
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After he became Vader, he found out his wife died.
Justifiable crash-out, to be honest
…and yet the death of Qui-Gon is meant to be the event that set Anakin’s fate.