Caesar is Happily Adopted by Will, and this bond with a good hearted human will forge Caesar's mindset for the remainder of the films.
Any interaction between Caesar and Will's father. Especially when the latter begins regressing into senility when Will's Alzheimers cure begins to fail.
Caesar's last meeting with Will in the movie in the redwood forest, where he tells Will, by speaking, that he is home. Bittersweet in that due to the Downer Ending, this would likely be their last meeting in their lifetimes.
As Caesar, Will, Caroline, and Will's father exit the Muir Redwood National Forest, Caesar has a brief, but thankfully nonviolent, confrontation with a German Shepard that, like him, is on a leash. After the brief ... "scuffle", Caesar, emotionally wounded by the experience, starts to question his role as a member in Will's family, asking nonverbally if he was a pet or not. Will, sensing the doubt within Caesar, faces him, and tells him that he is not a pet, but his son.
After Caesar exposes the other apes to the 113, you see the next morning all of them slowly rising, seeing the world in a new light thanks to their gifted intelligence.
An overlooked moment, Caesar puts the unconscious Dodge in a locked cage before releasing the other apes. Despite his cruel and sadistic behaviour to the primates, Caesar did this rather than killing him or leaving him at the mercy of the other apes. He also does this to Rodney but in a gentler way as he stops the apes from beating him to death and gently moves him into the cage rather than rendering him unconscious, and Rodney clearly recognises this and is grateful for Caesar's mercy.