Tyson has the beginnings of stress-induced split-personality disorder. *
The Soldier is a shield for Tyson, it protects his mental state.
As mentioned in his description:
Tyson can avoid stuttering completely and be completely in front of his actions, but only in short stints. After his time with The Colonel Tyson had been damaged physiologically, mentally, as well as physically. He was still the solider he once had been, but only in times of need. In the heat of battle or when medical care was needed The Solider comes out, as strong as he’d been in Afghanistan, but as soon as that need was taken care of he slips away, using the thousands of broken shards of submissiveness Tyson has become as a shield to hide behind.Tyson has been too messed up to maintain that nature indefinitely. When there was need he could be in control, but afterwards he hid away again. It exhausted Tyson to take on this soldier like nature, but when in need his instincts took over and dropped his shield. That strength was always there and occasionally bleed across when Tyson felt strong enough about a topic, but otherwise it hid behind Tyson’s submissiveness for when it was needed.Tyson isn’t that aware of this, nor does he know that it is the beginnings of stress-induced split-personality disorder. He knows that when threatened he would be stronger, more like he had been in the army, and that it felt like it wasn’t him doing the actions he had, but he doesn’t know that isn’t just his imagination.
The Soldier is purely instinctual survival, a defence Tyson’s brain has created to protect him from the trauma of his past.
A fragile shield that Tyson can’t choose to wield or lower; often only broken by direct pain that wasn’t accompanied by adrenaline, or after the adrenaline - or conflict - had long since faded. Tyson isn’t even aware of The Soldier, beyond a sudden surge of inner strength and acting on instinct. He has no choice, it’s an instinctual reaction.
The Soldier is aware of a strong desire to protect Tyson, but doesn’t recognise himself as being separate from Tyson. Though Tyson could defend himself the majority of the time, situations that evoked an unnervingly deep emotional response are more likely to trigger his stress-induced split-personality-disorder than purely physical threats that Tyson has endless plans to survive.
As such, they are rare and The Soldier hadn’t devolved his own full personality separate from Tyson, he was only a piece from Tyson. He existed to protect. The Soldier is very mission orientated, needing a focal point even more than Tyson goes to even exist.
The Soldier doesn’t stutter and he doesn’t bother suppressing Tyson’s Synesthesia. He isn’t bound as tightly to Tyson’s OCD ticks, and none of his nervous twitches appear, but some of his older most ingrained OCD habits happen as simple muscle memory from endless repetition.
* Stress-induced split-personality disorder isn’t an exact medical term, but extracting The Soldier from Tyson’s Obsessive Compulsive Disorder, (Generalised & Social) Anxiety, Post Traumatic Stress Disorder, and other potentially un-diagnosed conditions (insomnia, depression, and eating disorders that may simply be symptoms from other conditions) to understand whether he has Dissociative Identity Disorder or Borderline Personality Disorder is tricky when Tyson refuses to even get treatment for the mental disabilities he’s confirmed to have.
The exceptions would be Chicago!Verse, Cat!Verse, and Veteran AU where Tyson is seeing a therapist with varying frequency and willingness. Chicago!Verse is a resigned allowance, Cat!Verse it’s slowly being broached by Jasmine who is qualified as a therapist to see if he could handle therapy yet, and Veteran AU where Tyson’s counting the days until his obligation to see the army’s veteran therapist ends.
For most circumstances, The Soldier comes from the beginnings of stress-induced split-personality disorder. However, to provide a distinction to those verses where Tyson is willing or unwilling seeing a therapist, The Soldier instead comes from Borderline Split Personality Disorder.
The verses where The Soldier plays a stronger role/has a slightly different stresser are Bioshock AU, MassEffect!Verse, and Earth!Verse; respectively, a side-effect of the Blind-Faith plasmid, potentially caused by the surgery on Tyson’s L2 implant, and the side of Tyson with complete control over his mutation.
The Soldier does not exist in the following verses: Army!Verse, Hogwarts AU, and all three Orphan AUs: Child!Verse, Child!Verse2, & Teen!Verse.