Clu 1: Extra Details & Theories - Personal Sacred Respect
When addressing Flynn, Clu 1 only ever addresses him as 'sir.' He does this repeatedly in almost every sentence.
This is one of the signs of Clu's respect for his User, but in his own way. It's hinted that a User's name is treated with sacred respect and is used to address one's own User, as seen here:
So, why doesn't Clu do it? Well, there could be several reasons.
One: Clu most likely doesn't know that it's a normal practice to address his User by his Username. Given Clu's function, he is not tied to any system, its norms, or any relationships to any programs. He may think similarly to other believing programs, but that doesn't mean he practices his beliefs the same way other programs do.
Two: Speaking of norms, it could be Clu's way of rebelling against them, as he shares that trait from Flynn, yet still finds a way to be respectful to him.
Third: To get this out of the way, it's possible Flynn could've had Clu address him that way, but I don't see this aligning with Flynn's character. So, it must be a personal choice by Clu. The reason behind this is unknown. It could be that addressing his User by his name is uncomfortable or too intimate for Clu.
Nonetheless, he must show his authentic respect, so he chooses the formal honorific, 'sir.' All these speculated reasons could be a mixture of all the above. What remains is that the honorific is a show of personal respect from Clu to Flynn.
On the other hand, when Clu isn't directly addressing his User, he does speak and think of his User by his actual Username.
