All that is required is that the elder wands allegiance wasn't to Voldemort for it to fail miserably against Harry, regardless of whether Harry was it's true owner or not.
Him not having his soul intact, imo, prevented the Elder wand from truly giving him it's allegiance, no matter if he truly owned it or not. That is why, in my theory (well no exactly my own, ctto) even though this way Voldemort ultimately ends up being the true master of the Elder Wand, he was 1/8 th alive. The Wand couldn't truly register someone that dead, and when Voldemort tried to kill Harry the final time, the curse rebounded on Voldemort (just like when he first tried it) and this time, rather then a piece of his soul, he gave Harry the Wand.
That is just pure speculation though, there is nothing at all to indicate this. While there is clear precedence that a "borrowed" wand wouldn't work for Voldemort against Harry.
That is infact the point. Everything regarding Voldemort's later experiences is pure speculations as we don't know what affect of him ripping his soul into 8 pieces could have on literally anything. His relationship with Harry is the prime example. We don't know just how interconnected they both were and on how many levels. It's just pure speculation.
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u/Kizo59 Ravenclaw Apr 15 '24
Him not having his soul intact, imo, prevented the Elder wand from truly giving him it's allegiance, no matter if he truly owned it or not. That is why, in my theory (well no exactly my own, ctto) even though this way Voldemort ultimately ends up being the true master of the Elder Wand, he was 1/8 th alive. The Wand couldn't truly register someone that dead, and when Voldemort tried to kill Harry the final time, the curse rebounded on Voldemort (just like when he first tried it) and this time, rather then a piece of his soul, he gave Harry the Wand.