Programs are born wearing masks. At first the masks are small, transparent, and soft to the touch. By the time the program grows into his or her suit and skin the mask is glass and can retract, nesting around the shoulders. This is natural: it comes standard.
Programs learn to recognize one another with their faces hidden relatively quickly. They use the masks often, after all: riding vehicles, fixing lines of code, fighting in the disk battles that offer the exhilaration of throwing one's own soul around. Programs like Beck and Brody learn to recognize one another through posture, through ease of movement or length of leg, when they are young. It's rare that a mask really hides anything. You can guess a lot about a person from how they walk and whether they hold their chin up. ("How do you know he's handsome?" "I just think he might be.")
This is why Beck's thoughts stall when he sees Tron's scars. Beck is fearless, a risk-taker, made to put his hands into the workings of machinery that might start spinning at any second. He is a mechanic because he was programmed to be. This is why his job feels like his home. But some of that instinct is disrupted when he sees Tron, because the red-lit mask his hero stalked behind had given absolutely nothing away. Caught in a potent mix of adoration and fear, Beck chooses, for once, flight over fight.
When he thought Tron was an interrogation program Beck shouted platitudes he has before, feeling familiarity buzz up and down his vocal chords. Worn data tastes just a little bit distinct. And although it was unintentional on Beck's part that means that Tron has to trust him, has to reveal his face eventually, because as intimate a feeling as it is familiarity is easy to fabricate. Programs made from repeating bits in a world made specifically to house them and give them an operable medium are always living with deja vu.
Beck's tenacity convinces Tron, or at least lessens his skepticism. Beck thinks that maybe Tron hit him and knocked his disk across the floor (its presence divorced from Beck pulling like a string) to see whether he would break under torture. Beck can still feel Tron's thin backlit hand clawing at the back of his head for a moment in a rough mockery of a father tousling his son's hair.
The Tron that Beck remembers wouldn't have used such base methods to test someone - although of course the action he takes next isn't base. Examining someone else's coding is reserved for doctors or the Users who find programs after they die. It's rude to look directly at someone else's information instead of figuring it out through the trials and tentative joys of friendship. The first clear image that emerges in Tron's hands is the shop, because mechanic work is what Beck was written to do.
Tron doesn't offer an exchange of information. He's still acting like an agent of Clu, a red guard, an interrogator. Tron the hero is only a figment made out of whispers. Some programs have seen him in his heyday: Beck saw him once long ago. But mostly he's a rumor, like the rumors about Users walking around the Grid or the City hiding a ring of dealers in black-market imperfections. Even after seeing Tron's face Beck has trouble believing he exists. Beck remains afraid. The word hero in his head retreats back to old languages he does not know and turns into the word for monster.
He has proof that Tron has survived monsters and maybe become one, because scars heal. Being a mechanic does not also make a program on the Grid a doctor but Beck knows enough to see that even the worst scars can be overwritten. Tron's were not. They shift and rearrange, shining white like new teeth. Whatever did that will not be easy to fight. It will not be far away, it will not be platitudes. (Even with the General at Beck's doorstep and his friend's dying disk clicking against his feet, Clu is far away and Beck is young and brash.)
Tron in the guise of his tormentor stood before him with shoulders hunched and hands clasped behind his back.
His tormentor said, "You're brave."
It was statement rather than a question, the opening volley in a game. Beck's bravery is a fact. No program can change their facts. Only Users can change, being brave or cowardly on their own secret terms packaged and delivered by a higher process no program can understand, and that is what makes them so feared and revered.
Beck idolized Tron because they were alike: Tron was also programmed to be brave. Taking the same name isn't much of a leap of logic if you already know that most of the wiring of your soul is, by necessity, identical.
Splitting Tron's disk, though, is going almost too far beyond decorum. The blue wires inside the disk glitter wetly, and Beck takes it automatically, as he would a tool at the shop.
It reveals itself just to be a mod for color, an outdated white that hasn't been in fashion since Clu took over. Beck is re-rezzed into something pale and shining that he doesn't recognize, and it is almost as if he's watching himself, his own stolen colors, as Tron walks away.
Beck's look of fear and disorientation reflects something else, too, a shiver that runs down to his smallest bits of data. When he first woke up in this room, damaged and bound by cuffs he started to unlock almost without thinking, Beck didn't see the silhouette of his hero when he looked at the man wearing Tron's mask. He saw an enemy, something that shivered and prickled at the back of his neck. His captor hit him with the flats of his hands before pushing his head down and wrenching away his disk. Instinct, which on the Grid is called programming, told Beck that the thin figure spotted sparsely with red lights was a mystery. An uncertainty. Distant but real Clu is more understandable than this face-changing, half-dead man in front of Beck's eyes. Tron has gone through things Beck can't understand. Even after he reveals his identity he he does not have body language that Beck can read. Tron is all mask, even when he shows his skin and his scars.
For this reason, Beck fears Tron more than anything else.