Yeah, Hunsiker was a jerk, but consider this: Imagine being chased by a vicious chimpanzee hellbent on brutalizing you for being angry your car's been smashed up.
Or worse for Rodney after Dodge accidentally kills himself, imagine being the poor bastard, getting beaten to death by a dozen or so angry apes, all too willing to pay you back for years of abuse. At least Caesar steps in to save the latter before it's lethal, putting Rodney in a cell for his own protection.
Koba himself. Out of all the apes, he's the most horribly scarred and demonic looking. It's also worth noting that Koba isn't a chimp, he's a BONOBO, who are very rarely violent, especially in comparison to chimps. Now, take this into account with how ruthless he is not just in this film, but in the sequel. What the fuck did they do to make him so brutal?
It wasn’t only the lab, but his previous owner as we learn in the interquel novel.
Caesar's first few moments in the primate center. Locked in a small cage, at the mercy of a threatening human "overseer" whom he can understand, and surrounded on all sides by angry chimps screaming and thrashing around violently.
Caesar's Big "NO!" will send chills down your spine.
Noticeably when Rodney is found by Will locked in the cell, he first says "he spoke". It's not the organized rebellion, the death of Dodge, or even his own almost lethal mauling, no, the think thing that shocked him most was hearing Caesar speak.
The end credits show an infected Hunsiker going off to his job as a pilot, and a graphic displaying the subsequent spread of the virus across international flight routes...
A deleted scene that came to fruition in the sequels: After Will walks away and lets Caesar and his followers live on their own, Koba walks through the forest, when he finds a hunter’s discarded shotgun. After a few seconds of him treating the gun like a normal ape would (even trying to eat a shell), he quickly figures out how to use it, loads the gun, cocks it, aims at the screen, and...BANG!!
, who are very rarely violent, especially in comparison to chimps. Now, take this into account with how ruthless he is not just in this film, but in the sequel. What the fuck did they do to make him so brutal?