Short story revised

Our story is set in a futuristic dystopian city. Its high rise buildings fill downtown and beyond as far as the eye can see in the distance. This is where M.A.R.K calls home. The vast expanse of the city makes him looks insignificant in comparison to a city that houses 30 million people.

M.A.R.K trudges along the street in usual fashion. He passes a group of three friends with their chest spheres glowing (this is a visual sign of happiness among robots) . M.A.R.K's isn't, never has. It would be unnatural for him not to be jealous but he's learnt to hide it after so long. 
He gets in to his taxi and drives off on his usual night shift. His taxi generally tends to be a lonely place. Just him and the road. Even when he has passengers there is never any communication, he picks them up, sets them down and gets paid, thats it.
Continuing down a road that is generally good for getting fares M.A.R.K notices what is a certain customer, a small, petite figure in the distance with her arm out stretched hailing him down. The only light on the street illuminates her casting an angelic light which makes her stand out from the general griminess of the city. 
M.A.R.K drives up and pulls over next to her, she walks across to meet him and leans in the window.

"Newtown" she says in a soft wispy tone

"O.K but it'll be a while, lots of traffic." M.A.R.K replies 

"I'm patient" S.A.L.L.Y replies before getting in to the back of the taxi. M.A.R.K begins the route.

A couple of minutes in to the journey S.A.L.L.Y leans forward and opens the glass divider that was separating the two and introduces herself.

"I'm S.A.L.L.Y" she says

"M-M.A.R.K" his reply is hesitant because of the fact that no one ever talks to him let alone a real female who introduced herself first.

"Pleasure to meet you" S.A.L.L.Y continues.

Shocked but overwhelmed with happiness M.A.R.K's chest sphere begins to glow slightly. This is the first time that anyone has shown an interest in him in years so it is understandable that such a small thing could cause a spike in his mood.
The conversion flows as the trip continues with M.A.R.K even pitching in at times. His sphere illuminates stronger as the journey progresses.

Everything halts when they approach a set of traffic lights stuck on red. The taxi sits in the lane surrounded by darkness, there are no other cars or pedestrians in sight as he eagerly awaits for the lights to change. He does not want to be here for long and it is evident with the nervy revving of the engine. Slowly he creeps forward, eager and expectant but he is halted quite quickly by a dark figure approaching his car side on. M.A.R.K barely has time to make out the attacker, a short, hooded figure with a bandana wrapped around the his face when an iron bar in the assailants hand is forced through his driver side window.
Confused but spurred on by instinct M.A.R.K exits the taxi and begins to try to deter his attacker. It works to some extent until two others join the first attacker. The fight continues with M.A.R.K waining some what until a cry comes from the other side of the car. 

"Move again and we'll kill her" Shouts one of the muggers.

M.A.R.K stands there paralysed by fear as he it caught across the head with a blow from the same iron bar used to smash his window. He falls to the floor as his attackers take his money and run off in to the distance. He turns his head in time to catch a glimpse of his attackers and S.A.L.L.Y as they flee the scene. What he sees confuses him, she is talking to them, touching them, laughing with them, just like friends would do. Why? was this all a set up? he asks himself. His mind can't take much more but just before he passes out his eyes focus to the foreground where his hand rests. He makes out the faint shape of dog tags (the form of robotic I.D) he must have wrestled off of one of the robbers during the scuffle. His eyes slowly defocus as he proceeds to blackout.

The next night M.A.R.K trudges along the street as usual. He approaches a trio of other robots as he walks. Instead of walking past he stops still. In his hand sits a small handgun, barely noticeable unless you know its there.  It seems heavy but manageable in M.A.R.K's palm as he grips it tighter. Pulling it up he watches the group of men turn around just in time for them to focus on the barrel of the gun before the trigger is pulled. M.A.R.K fires off 9 rounds, three per person until the clip is empty. In the background a female figure runs out of a house in to the street. She kneels beside one of the bodies on the floor taking a bandana out of the back pocket in an effort to stop the large amount of oil flowing from one of the several bullet wounds. This is S.A.L.L.Y and the victims are the three attackers. 
M.A.R.K shows no remorse for the brutal assault as he pulls of the set of dog tags from his pocket and throws them on the the corpse at which S.A.L.L.Y is knelt beside. On the dog tags reads the address at which M.A.R.K found his attackers. 
Casually, he turns around continues down the road placing the gun down the back of his pants and covering it with the back of his jacket as if he had never even stopped.