I touched on this in the comments on my last blog, but it's something that really interests me so I thought I'd put my ideas on the subject out here in the open for you all to see and do what you will with.
Zoan fruits grant the person or object they are bestowed on the attributes and powers of a specific breed of animal. They allow the user to take on two new forms initially, a hybrid form and an incomplete version of the animal their fruit pertains to. We all know this.
Now, when an inanimate object 'eats' a zoan fruit, they are given sentience. They have a mind and are able to experience feelings like loyalty and fear. They possess an intelligence that was not present before the fruit was integrated into the object. The obvious conclusion to be reached from this is that inside a zoan fruit is a living representation of the particular animal that the fruit represents. When the fruit is combined with a weapon that has no control over itself, this archetype's soul gains a body that it has almost complete control over. However, when the fruit is eaten by a human, this is not the case. In some cases, Rob Lucci's being the most prominent, the person will experience some of the instinctual urges associated with the animal, but for the most part, the human seems to remain unchanged. So, in this case, what has happened to the 'soul' that once existed inside of the fruit? Has it been merged with the mind of the person who ate the fruit? Some might say so, but then another question arises. In the case of Awakened Zoans, the human who once ate the Devil Fruit seems to have been overcome by the animal that resided in the fruit, losing themselves entirely to their ingested instincts. You could say that perhaps the more powerful animals, with the more violent and urgent instincts (to hunt, to kill) would be the hardest to keep under control, however, of all the Awakened Zoans to have been seen so far, none have been carnivores. A cow, a rhino, a zebra, a koala and a chihauhau. None of them seeming to be driven by instinct, in fact a few are entirely domesticated animals. So is it something else then, perhaps something in the person who eats the fruit that results in this loss of control? Does, perhaps, the 'soul' of the Devil Fruit usurp the weaker hosts body, seizing control for themselves?
With regards to this, I think we have to consider how these zoan 'souls' act. Funkfreed and Lassoo were highly obedient, following their masters every command. This suggests that the archetype's mind is inately subsurvient. This is backed up by how the Devil Fruit seemingly offers up it powers to the person who eats it, offering little resistence. But if so, why do the fruits rebel in the cases of the Awakened Zoans? Do inanimate object zoans in fact owe their meekness to their host bodys, who were originally tools, meant to obey? With regards to this argument, Smiley, the Axolotl formed from poisonous gas, didn't show any particular obedience to Caesar, who was spared from a pitiless death simply due to his own Devil Fruits attributes. Poisonous gas is not inclined to obey orders, and so this could be seen to support the idea that inanimate object impose their own 'instincts' on the 'soul' of the zoan they have 'eaten.' There is one more fact to be considered, however.
Chopper. Tony Tony Chopper was a reindeer who ate the Hito Hito no Mi, ingesting the 'soul' of a human. Now I ask you, is Choppers empathy, compassion, childlike glee and naivety, his impressive intellect, his ability to dream and inherit dreams, are these the attributes of a reindeer, or a human? In Choppers case, it would truly seem that he is much more akin to his fruits species than his natural one, even more than Rob Lucci. He feels intense emotion for his adoptive father, he cares deeply for any facing mistreatment, especially at the hands of intellectuals, it seems that he has almost entirely become a human. Which brings us to the final point. Choppers "Monster" point. I have previously put forward the idea that it is in fact his own Awakened form, resulting form his overly volitile genetic make-up cortesy of the rumble balls. If we take that assumption to be true, then the question must be asked, why is his Awakened for more animalistic than his normal one? If Chopper gained all his human features from the 'soul' within his Devil Fruit, and his Awakened form involves losing himself to his ingested instincts, then why doesn't he become more human? I believe this to be the reason. The 'soul' that controls Tony Tony Chopper's body is not that of a reindeer, his own mind was overwhelmed the day he ate the Hito Hito no Mi, and in it's place, an more powerful human mind resides in Choppers body, having subjugated the original occupant of the body in the same manner that a human would if they ate a Reindeer Devil Fruit. When Chopper would eat that third Rumble ball, his molecules would become sufficiently agitated for the animal to regain control, and the huge "Monster" point to be achieved as the opressed reindeer returns to the surface. The other Awakened Zoans ventured to deep into the powers of zoans, perhaps trying to compensate for the lack of power afforded by their fruits and lost control permenently, I'm assuming Chopper returns to normal because his reaching "Monster" point is relient on the Rubble Balls effects which wear off.
I realise that took ages and sounded a bit like a fucking essay, but I wanted to be formal and do the idea justice, cause it's pretty scientcy and pretty metaphysics-y. tl;dr: IS CHOPPER REALLY CHOPPER??