|“||I did two tours in Iraq. Special ops, Darfur. The Congo. I've seen suicide bombers and child soldiers, so hopped up on speed that they could barely talk. But they could sure as hell shoot an AK.||”|
— Cole to Sam
Cole Trenton is a former US Marine seeking revenge on Dean Winchester and spent much of his life training and preparing himself in order to hunt down Dean. Cole's father, Edward, was killed years ago by Dean and he witnessed it as a young boy.
Cole was a self-described "military brat" as a kid since at least one of his parents was in the military. Growing up on a military base, he became best friends with Kit Verson, a friendship that lasted into adulthood.
Cole has an older brother he calls Davey. When Cole was a kid, he and Davey tried to impress some girls at the local DQ by Cole riding on his brother's handlebars and Davey performing a wheelie. Cole fell off of his brother's bike and broke his arm for the first time in the process.
On June 21st, 2003, a thirteen-year-old Cole Trenton woke up to the sound of a struggle coming from the downstairs of his house. When Cole went downstairs to investigate he found that his father, Edward Trenton, had had his throat slit in a struggle with Dean Winchester. Dean let Cole live, and he left the house. Since then, Cole has harbored vindictive resentment towards the man who killed his father and has devoted his life to training and preparing himself in order to track down Dean and exact revenge for his father's death.
Not much else has been revealed about Cole at this stage, except that he was a former United States Marine. According to Cole: he served two tours in Iraq, and according to him he operated as Special Operations/MARSOC in Darfur and the Congo. (Although there has been no documentation released to the public about MARSOC involvement in Darfur or the Congo, it is possible that Cole was apart of a Covert Operation/Action; meaning paper documentation could be held in secret or expunged). As a result of possibly his time in the military, Cole has a friend in Military Intelligence who owed him a favor for an unknown reason to such an extent that he would reveal classified information to him if he asked for it.
Aside from his hate for Dean Winchester and military service, Cole has other occupations in his life. He lives in a middle-class house with his family, consisting of his wife and son. He also keeps an arms locker in his house, similar to what hunters been shown to have - except without the tools necessary for fighting supernatural beings.
An unknown party sends Cole a fax of a photograph of Dean, taken from the surveillance footage of Dean's attack at the Gas-N-Sip, with the word "Yup" written on it. Cole's wife is seen crying about this because she sees it as him going on another "deployment oversees", except in this case he's going to get revenge for his father's death. Cole packs up a bag of weapons and ammunition, and sets out on the trail. Sam Winchester's car suddenly breaks down while he is on the way to Dean and Crowley's location. Cole finds him and pretends to inspect the engine, Cole reveals that the reason the car stopped is because of a "killswitch" that Cole himself is able to operate via remote. Before Sam can pull out his gun from behind his back, Cole knocks him out cold. Sam wakes up to find himself strapped to a chair, Cole explains that he is using Sam as a bargaining chip to lure Dean and kill him. Sam warns Cole that Dean is a monster (aware that his brother is now a demon), but Cole naively rebuffs saying that he knows he is a monster and that now Dean is the prey and Cole is the hunter. Cole calls Dean and demands a trade, but Dean is apathetic towards his brother's capture as he warned Sam not to come looking for him, so it's his fault he is in his predicament but vows to kill Cole down the road.
When he receives a phone call from his son, Cole pretends to be unaware of a knife falling from the pocket where he retrieves his phone, and promptly leaves to take the call, knowing that Sam will try to escape and track down Dean. Cole follows Sam to Dean and when the two are talking in a bar Cole throws a can of tear gas through the window, forcing Sam outside for air, where in his weakened state he falls unconscious. Dean however appears unaffected, and goes outside to face Cole. Dean shows no remorse for killing Cole's father and it is clear the darkness as a result of becoming a demon is growing. Cole and Dean fight but Dean easily defeats him, he does not kill him however, later on whilst in the car with Sam, Dean explains that Cole will know that he finally tracked down his father's killer, only to lose and find out he could do nothing against him, (therefore condemning him to a torturous life as a hunter). At a library, a badly beaten Cole asks the librarian for all the books she has on demons, showing that he is still set on getting revenge.
Cole tortures a demon for information on Dean, still intent on getting revenge and tracks him down just as he captures Rowena. Cole forces Dean to let Rowena go and throws holy water in his face, believing him to still be a demon. After Dean explains that he's not but wasn't when he killed Cole's father either, the two engage in another fight. Dean once again gains the upper hand and holds Cole at gunpoint, but instead of shooting him, asks him for five minutes to explain and then Cole can do whatever he wants to him. Dean gives Cole the gun and Cole lets him explain: Cole's father was a monster of some sort. Dean never encountered it before or since so he doesn't know anything about it beyond that the monster ate livers and killed people for them. Cole asks about why his father called for him then but Dean insists it was a trick and that his father may have come to kill Cole or his mother. When Sam turns up, Dean convinces Sam to lower his gun and tells Cole that he's beyond saving and is bound for a bad end, but that Cole isn't. Sam and Dean remind Cole of his family and he eventually lowers his gun and goes home to his family, finally accepting the truth.
Months later, Cole gets a call from Jemma Verson, his best friend Kit's wife telling him of how weird Kit was acting. Concerned about his friend, Cole goes to visit and discovers Sam and Dean at Kit's house. Recognizing that they must think Kit is a monster, Cole refuses to leave them alone, worried that they will kill Kit. They explain to Cole how Kit and his friend Rick apparently got turned into monsters on their last mission as Rick drank all of the fluids of a woman before being killing himself and Kit is displaying similar symptoms. As they believe that something happened on Rick and Kit's last classified mission, Cole offers to use his contact in Military Intelligence to find out, on the condition he comes with them as he doesn't want them to kill Kit. Sam and Dean reluctantly accept his help and they learn from his friend that Kit and Rick's last mission was to rescue a prisoner of war in Iraq and that it didn't go well with a video sent with the message revealing that the soldier attacked them and was killed. This causes Sam and Dean to figure that whatever happened to the soldier happened to Kit and Rick and it turned them into monsters.
While Sam and Dean now believe he's a monster, especially after he drains a gas station clerk of blood, Cole is still insistent on saving him and leaves Sam and Dean when it becomes apparent they will kill him. However, when Cole goes to check out a cabin that Kit might be hiding at, Sam and Dean follow him. Cole finds Kit who attacks him and infects Cole with a Khan worm before escaping. Sam and Dean realize what they're dealing with and while Sam goes to find Kit, Dean decides to try electricity to get the worm out of Cole who finally understands and appreciates what Sam and Dean do. Electricity doesn't work and it nearly kills Cole so Dean decides to try extreme dehydration after realizing that the worm is acting like a parasite, drinking every fluid it can find and drying out the host causing him and Cole to theorize that dehydration might force it out.
The two turn Kit's cabin into a sweat lodge and the experience causes Cole to finally understand what his father went through when he got turned into a monster. He asks Dean to kill him too if he can't be saved, but Dean is insistent on continuing to try and ties Cole up at his request. Cole eventually breaks free and attacks Dean who begs him not to make him shoot, but before he has to, the Khan worm leaves Cole and tries to infect Dean who kills it. However, while they now know dehydration will work, it is too late for Kit who Sam is forced to kill to save Jemma. Though Cole is saddened by his friend's death, he accepts that it was necessary and forgives Sam before returning to his family, telling Sam and Dean he hopes not to see them again and thanking Dean for saving him.
Cole is shown to be loving and deeply loyal towards those he cares deeply about, particularly his wife and son and his life-long friend Kit Verson. He also appears to be haunted by the atrocities he saw committed during his work in Special Forces, getting emotional when describing what he witnessed to Sam. He also shows himself to be resourceful and intelligent, using a kill switch to disable Sam's car and then letting Sam escape when torture wasn't working so he could follow him instead. Cole has shown a tendency to nickname people, calling Sam "Sammy" and Dean "Deano."
For most of his life, Cole's major goal was to get revenge on Dean Winchester, the man Cole believed had murdered his father. When finally confronted with Dean, Cole tells him that he prepared for half of his life for their fight and that his nights are haunted by nightmares of his father's death. Cole was obsessed with his revenge to the point that he was willing to torture and threaten to murder an innocent man to get it, though its unclear if he would've actually murdered Sam or not. After meeting the demonic Dean, Cole quickly adjusted his world view to include demons and trained to fight them instead so he could take down the demonic Dean. After finally coming face to face with Dean a second time, Cole only reluctantly permitted Dean to explain himself and had a hard time accepting the truth about his father's death after the way he'd built his father up over his entire life. However, he came to accept the truth and gave up his revenge and returned to his family.
After giving up on his revenge, Cole returned to being a family man though he didn't hesitate to go back to hunting monsters to save his friend Kit's life. During this time, mainly due to seeing Kit's possession by the Khan Worm and his own possession by the monster, Cole grew an understanding of what his father had become and why Dean killed him. This experience seemed to cause Cole to come to terms with his father's death and to forgive Dean for it, requesting that he be killed too if he couldn't be saved so Cole too wouldn't become a monster.
Although he's just a common human, after a training throughout half of his life (partially because his training and experience in the Marines) he acquired some abilities. After the first meet with Dean in demon state, he quickly gained some basic hunter skills.
- Weaponry - He is skilled in the use of various weapons with years of training and practice in the Marine Corps and on combat deployments to foreign countries such as Iraq, Darfur, and the Congo. It's safe to assume that he knows his way around firearms and is very capable with them.
- Martial artist - He is skilled in hand-to-hand combat and other forms of martial arts, although his skill cannot be compared to Dean as a Knight of Hell. When he fought Dean after he'd been cured, Cole was able to match him for a while before he eventually lost again.
- Basic Hunting Skills - After learning of demons from his encounter with the demonic Dean Winchester, Cole did research that has granted him basic hunting skills, at least towards hunting demons. As a result, Cole knows of the effectiveness of holy water and can use devil's traps against demons. It is unknown if he can perform an exorcism once he has a demon captive but it is likely.
- Cole was human, while his father was a monster. According to Dean, Cole's father was once human too but got transformed into a monster at some point.
- Cole's experience with the Khan worm caused him to have a new understanding of what Dean did. Not only did he seem to forgive him, but he also requested that if Dean couldn't free him from the Khan worm, he kill him too. However, Dean managed to save Cole unlike his father.
- According to Cole, he's a military brat, indicating that either his father or mother was in the military. Cole may have also been a rowdy kid given what he said about his antics with Kit Verson when they were kids.
- Cole calls Sam "Sammy" and Dean "Deano." Demon Dean referred to Cole as "Inigo Montoya" while taunting him about his father's death.
- Due to his time as a Marine, Cole apparently has some powerful connections as someone found out about demon Dean's killing of Drew Neeley and informed him and he has a friend in Military Intelligence who was able to find out about a classified mission and send him information on it.
- Cole's desire to seek revenge on Dean due to the death of a parent, is similar to Jacob Pond , who promises to also hunt down Dean for killing his mother. Both Cole's father and Jacob's mother were monsters, which is why Dean killed them.
- Despite stating he had an older brother named Davey while talking to Sam in Black, the family picture shown in the flashback of Reichenbach only showed Cole and his parents with no sign of a sibling.