It made no sense at all. None.
There was no logical reason why paint and scratches in the wood should stop a predator from hunting in their home. Therefore, there was no logical reason why Caesar should let the two humans walk the entire perimeter of his new home drawing and carving random little pictographs as they went. Neither man could explain why the magic words would work, merely that they would work.
But perhaps most baffling of all, was they fact that Caesar allowed this nonsense. Why? He couldn't even answer the question for himself. Or maybe he could. Caesar couldn't shake his belief in Sam and Dean themselves. As capable leaders. As good men. As people that could be trusted.
Because he did trust them, on the strength of instinct alone.
He had nothing specific to point to and say, 'This. This is why.' Except maybe a small speech, thrown at him minutes after he had woken up. The one about leadership and exhaustion and resentment and recuperation. About how Caesar wasn't alone in these things. There was a kind of recognized kinship there, leader to leader, that he would never find among his own kind.
Maybe it was foolish, trusting a human again. But Caesar could not pull back now. Besides, it wasn't like a little paint and a few scratches would hurt anyone.
The humans in question completed the circuit. Despite the darkness of the late hour, Caesar could see satisfaction on their faces and the subtle relaxation in their shoulders. They really did believe in all this. Dean even clapped Kerchak on the shoulder to celebrate a job well done. Kerchak, the angry ape from the show-down, had agreed to escort the men and was now gesturing wildly over some new (if less angry) discussion. Probably the pointlessness of the exercise.
Later, Caesar would have to slow down the sequence of events in his mind to truly process everything that happened in such a short span of time. Not because everything happened so fast, he had great reaction times after a life of combat. Rather because his scientific and down-to-earth mind did not want to accept what his eyes told him.
Even as he watched, a black form grew from a formless shadow into a solid beast, vaguely humanoid, but sporting claws. Kerchak, still gesturing wide to encompass the campgrounds, could not know there was a monster coalesce silently behind him.
But the Winchesters did.
Dean flung himself forward and somehow managed to tackle the bigger, heavier ape to the ground. Meanwhile, Sam lunged for the torches. He swung the left like a baseball bat to force the beast back from Dean and Kerchak. He jabbed the right forward in a neat fencer's extension to cause the monster to shriek before exploding into whisps.
"Everybody, FREEZE!" Dean bellowed, his deep voice echoed throughout the camp.
Instantly and instinctively, every ape stilled at the sound. For a few heartbeats, the world stayed frozen. In those few moments Caesar could have sworn that he heard the very shadows breath... scenting the air like a predator who had lost sight of its prey.
Anger swelled to block out Caesar's fear. His apes were not prey.
"Dean?" Sam stood poised on the balls of his feet with the torches. Ready to move again.
"I haven't seen these things since Purgatory," Dean answered softly. "They track movement, don't move and they can't find you. Like the old Jurassic Park movie T-Rex."
"Fire kills them?" Sam needed to be sure.
"Light," Dean corrected. "Any kind of light. They must have been really hungry to come so close to the fires and torches."
"Great," Sam huffed.
A wind gust shifted the tree branches. Caesar watched in horror as their shadows took a fraction of a second longer to move. Careful to move his jaw as little as possible, he needed to know "Why now?"
"Weak moon, partly cloudy night," Dean speculated. "In a couple days, when there's no moon at all... ding, ding, chow time."
"No!" Caesar barked, furious at the thought.
His father's rage finally broke what little self-control little Cornelius had. The boy-ape screeched in distress and tried to race across the camp to Caesar's protective side.
NO! Caesar's mind screamed. He watched, helpless, as the shadows all around them spat out their nightmares. The ape leader was too far away to save his own son.
Again.
But the Winchesters weren't.
Once again Dean flung himself forward, scooping the child into his arms. Razor sharp claws meant for the scared little boy sliced through the human's tough leather jacket and the tender skin beneath. A hiss of pain through the teeth was all the movement Dean would allow himself while he pressed Cornelius tightly to his stomach.
Without movement to follow, the shadows became merely shadows.
"Dean?!" Sam didn't dare run to his brother's side.
"Flesh wound," Dean reported dismissively. "Hey, its okay, little guy." Dean's voice crooned low and gentle to the child in his arms. "You're okay. Everything will be fine. I just need to to hold as still as you can while us big, bad humans go kill the big, bad monsters, okay?" As Dean talked, Cornelius began to relax.
That's when it really hit Caesar: Dean could not know that Cornelius was Caesar's son. Dean risked and received injury to save an ape. Not because of who the ape was. Not because he needed to be on the apes' good side. Not to curry favor with his captors. But because Dean Winchester saw a scared child, irregardless of its species.
It was then that Caesar knew. If they survived the night, he would not worry about the threat the Winchesters might have represented.
"Not to interrupted the Hallmark moment, Dean," Sam broke in. "But how do the 'big, bad humans go kill the big, bad monsters?"
Dean surveyed the campgrounds. And then flashed a grin at his brother. "I have an idea."