So after some late night realisation, I like body horror. You think this would not be surprising to me, but you would be wrong. Anyway here is another headcanon I have been think about for Spider.
When Spider is captured in ATWOW, that explosion led to him being critically wounded and resulted in the RDA needing to do emergency surgery to upgrade him with cybernetics augmentations. When Spider wakes up, he finds himself in an interrogation room, cold and alone. He walks to the one-way glass and recoils in horror and screams as he looks at himself.
He finds that his eyes have been replaced and only sees 6 black orbs where his are supposed to be (1 in each eye socket and 2 above and below his main 'eyes'). He tries touching them or trying to pry them off, only to experience a blinding pain. It now dawns on him that this is not a dream and that this is a permanent transformation.
The story continues with Spider being interrogated in NeuroSec by Ardmore, to the point where now the boy is hemorraghing while he is still strapped into the machine. It's a horrific sight to see for everyone in the room, even Ardmore silently shudders but continues the interrogation because there is too much on the line to not get this prisoner to talk.
Quaritch can no longer take it and shuts off the machine. Putting aside, whether or not this is his son (him being a clone and all), even he cannot stand by and let a child be tortured this long unnecessarily.
Unfortunately, the damage is already done and Spider needs more cybernetic upgrades just to function due to the brain damage. When he wakes again he is in the recom's barracks with a IV drip stand connected into him. However, its not in his arm. As Spider feels around and follows the IV line, he now finds it connects into his spine - a new metal spine. His shaking hand finds that the metal spans his entire spine from his tailbone to the base of his skull.
Spider should be screaming and crying and horrified by this forced change to himself, but the torture by NeuroSec has done untold damage, even if the new implants have resolved most issues. Spider can't feel anything, no fear, no tears, nothing. Spider knows that he is forever changed and wont be accepted by Eywa now but he just can't grieve his chance to be with Eywa even in Death.
As the Recoms take Spider out into the Pandoran wilderness to guide them, he keeps getting attacked by animals. It seems that the metal in his body outweighs the effectiveness of the stripes.
Before long, Spider has been unwillingly transformed into a cyborg with far more metal than flesh existing. A scientist at Bridgehead once described him as "A Na'vi Adam Smasher" and after Spider's quick digital search (Being permanent connected with the Internet took a lot of getting used to), he somewhat agreed. He was a hulking frame of metal and synthetic muscle. His natural hair was long gone, replaced with a synthetic variant that looks normal at a glance but feels and looks wrong when you get close enough, the colour being too muted compared to his former natural curls. A thick tail attached to his frame that sways when he moves and doesnt react to anything but his movements. His cybernetic spine has been further upgraded to have a Kuru or at least, the human version. A bulky and jagged version that moves on its own and looks like it could cut you in one motion. The design choice was intentional by Ardmore and the RDA to mock his values and beliefs that he still hung on to desperately, despite having no strong feeling towards Eywa anymore - Spider just knows he needs to hold onto this belief if he wants to survive this with his sanity.
By the end of ATWOW, Spider is a shell of his former self. Formerly, a young boy with a great joy and love of life, is now a hulking behemoth that functions as a machine more than a person. When Lo'ak, first sees him on the Sea Dragon, he screams at him, yelling about what has happened to Spider.
For the first time since he stopped feeling emotions, Spider cries and sheds tears. Lo'ak doesnt realise that the monster before him is Spider. He is yelling and cursing the abomination before him not realising that this is the moment that Spider breaks and loses all hope. What chance of a happy ending is there, when even his brother is cursing him and doesn't see him?
I hope you enjoy this, because there is an alternative to this AU that I would love to write but it may be too much. We shall see.
PS. Can you tell that I love Cyberpunk 2077?