To unlock the "JUST A MACHINE" trophy in Detroit: Become Human, you must convince one character to kill another at a specific point in the game. The ability to unlock this moment depends on the characters' relationship. The most efficient path to this scenario is described below.
*** Spoiler - click to reveal ***You need to get Hank very hostile to Connor before the chapter called "THE BRIDGE" so that, in that scene, you can provoke Hank into killing Connor. The easiest way to do this is to remind Hank that you're a machine at every turn. He doesn't like seeing you get killed and come back from the dead, and he doesn't like you showing a lack of empathy. So die as often as possible and be cold and ruthless. In the confrontation on the bridge you have ample opportunity to get him mad, but if he's even remotely warm to you he won't shoot.
Here's the specific path you can take to get to this ponit:
Chapter - THE HOSTAGE
You don't know Hank yet so this can play out however you want, however I recommend getting Connor killed to be able to go for another trophy (see below the spoiler tag). The easiest way to do this is to immediately go out to the hostage after you have spoken to the officer in charge. Walk straight up to Daniel and use a cold approach, dismiss the helicopter and then annoy him until you get the option to sacrifice yourself.
Chapter - PARTNERS
Locate Hank and then spill his drink to get him to leave the bar. At the crime scene, find all the necessary clues to find the android (see this guide). There's no real opportunity to rile Hank up further without risking losing the android, and its best that you find him for the next scene.
Chapter - THE INTERROGATION
You want to get the android to kill you here. Analyze the photos and the android, and then choose to probe its memory when you get chance. When the android starts self-destructing, intervene. It'll shoot you and itself. Hank's opinion of you will take a dip.
Chapter - WAITING FOR HANK...
You can learn about Hank in this chapter for the below trophy, but it's not necessary for this current one:
When Hank shows up, just launch straight into the case files when you have chance, no need to get to know him. Hank will be almost hostile from the get-go just by seeing you back from the dead. Annoy him as much as you can when he doesn't seem to want to get up from the desk towards the end of the scene.
Chapter - ON THE RUN
You want Kara to get caught by the police. The easiest way to do this is to have Kara and Alice stay in the squat rather than the hotel during "FUGITIVES". Play out the beginning of this chapter as Kara and eventually you will switch to Connor. Head straight through the front door of the squat and speak to the android. Locate Kara and Alice under the stairs. A chase ensues, make sure you keep up until they get to the fence next to the highway. Make sure Kara passes her QTEs on the first side of the highway. When Hank tries to stop Connor going after them, refuse him and get onto the highway. You now just need to ignore all the QTE prompts for Connor to get run over on the first side of the highway. Make sure Kara passes her QTEs on the far side of the highway if you want her story to continue.
Chapter - THE NEST
During Hank's lunch break, again his opinion will dip when he realises Connor is once again resurrected. Let the conversation play out. Get to the crime scene and look at anything in the main living space (this seems to trigger interactivity in the bathroom.) Sample the contents of the sink and pick up the deviant's temple ring on the side of the sink. Investigate the stool in here and the fallen birdcage in the living room to establish a series of events that leads you to the attic space. Your target will jump you and run away. Chase after him. When you get outside, chase the android until your first opportunity to choose to go through or around a big white tent. Choose whichever, what's important is that when you vault over the roof and start sliding down the glass you need to stop pressing anything. Let the QTE timers run out and Connor will eventually plunge to his death from the edge of the roof.
Chapter - RUSSIAN ROULETTE
Again not many opportunities to get Hank hostile in this chapter so let is just play out. Once you deliver Hank a fresh pair of clothes you are free to explore. Head straight for the kitchen table and scan the upturned photo frame to get details on Hank's son.
Chapter - THE EDEN CLUB
Follow this guide to ensure that the Tracis are killed, which Hank really doesn't like.
Chapter - THE BRIDGE
Here we go. Hank should be fully in the "HOSTILE" column at this point. Go over and talk to him. Ask him a personal question and then ask him about his son for an extra little dip in your friendship meter. When Hank asks about the Tracis be cold. When he pulls his gun, be aggressive. When he asks you if you are afraid to die remind him that you are not actually alive. If his hostility is high enough, Hank should shoot Connor and you will unlock the trophy when you get to the flowchart.
Quick note: There is another opportunity for Hank to shoot and Kill Connor, provided that Connor has died so much that he automatically gets the rooftop sniper scene near the end of the game. However even though Hank specifically says "You're just a machine" while he's killing Connor, this scene and outcome does NOT unlock the trophy (at the time of writing). It has to be done during THE BRIDGE.
It's worth going for this trophy at the same time as:
And likely impossible to achieve in the same playthrough as: