He was never put in any kind of positive light or ever given the benefit of the doubt in the entire series, he's slowly killing Naruto and he couldn't give less of a shit about him, he just wants to be kept alive until he finally fully possess Naruto, which he tried several times already, including in the latest Konoha invasion where you know, the 4th Hokage, the series messiah, told him to fuck off and stay inside his son's seal.
Just because a Tailed Beast is being unjustly possessed and used as war tool by human people that doesn't suddenly make him an misunderstood beast who actually deep down is all chocolate and sugar.
When Shukkaku possessed Gaara in the first Konoha invasion he wasn't "Hey, i'm in control now! Now i'll take revenge against the fuckers that did this to me!" it was more like "Hey, iīm free! Now i can wreck shit up while i sing about it! Fuck yeah!"
The number of tails and quantity of chakra is completely irrelevant to whether a Tailed beast is evil or not, Hachibi's not evil but so far he seems to be the exception to the rule since we have no idea about the personality of every other one.
Ao is like the Kakashi of the Mist village. Composed and cool motherfucker.Ao has more personality hense would be the better candidate to come out of this predicament alive. Fuu's gonna switch to early then Ao's gonna fall in a way that it cuts the binding on his hands. As stupid as this may sounds Ao has to kool of a personality to die. If after the body swap he was freaking out histerically like a chicken with its head cut off then he'd die. Hes handling this situation way to calmly, i personally would've been freaking out if i was in a puppet's body staring up at my enemy in my body. Hopefully this all happens before the Mizukage and chujuro shows up though, or else they'll take the Fuu imposter Ao for the real deal.