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Harland Doyle is Jack Carver's main contact on the island Carver was washed up on.
He is an undercover CIA Agent working as a scientist on the island to uncover what sort of work is going on there. Though he is aware of the purpose of Dr. Krieger's unethical experiments, he does not reveal much more of his identity or reasons for being there until later on in the game.
In Far Cry Classic, after killing Dr. Krieger in his main facility, Doyle informs Jack Carver and Valerie Constantine that he deceived them and plans to make a fortune off of the acquried mutagen. After this speech, Doyle is now the controller of all trigens (and possibly, the remaining Mercenary forces) that remain on the island.
In Far Cry, Doyle first contacts Jack via a radio left in an old Japanese bunker. At first, Jack is skeptical and does not trust him, but Doyle reassures him by saying that the radio has a bio-reader and that he could have ratted him out by this time if he was against him.
Doyle acts as an instructor and assistant throughout Jack's journey, telling him where and how to locate Val, and giving him intel about the threats ahead. When Jack eventually rescues Val, he learns from her that she is an associate of Doyle's, and that he is a scientist on the island working undercover for the government.
Upon nuking the Mutagen facility, Jack and Val are captured by Krieger and taken on board a helicopter. Jack is kicked off but survives, and finds another radio next to a helicopter wreck downstream. From there, he resumes contact with Doyle, who tells him Krieger's whereabouts and that Val may be held captive by him. Jack heads to Krieger's office and finds that Krieger has mutated himself. He kills him along with his bodyguards and rescues Val, only to find her in a much more infected state than himself, as the two became contaminated by the Mutagen while in the facility. Doyle appears as a hologram in the middle of Krieger's office, and informs Jack and Val that he has betrayed them. He plans on selling the Mutagen to become rich; using the two all along to do his dirty work (which was killing off Krieger to steal his research and thus ensure the Trigens would not exact their revenge on him). Jack, infuriated at Doyle's betrayal and in need of the antidote, begins to make his way to Doyle's office at the peak of the island's volcano to confront him.
As Carver battles several Trigens and some Elite Guards at the base of the volcano, Doyle frequently radios and taunts him. Upon meeting Doyle for the last time, Carver shouts "Well, this wasn't in the plans right?" and promptly shoots Doyle. The wounded Doyle then hysterically tells Jack that through killing him he will achieve nothing, and that he cannot change the future, to which Jack replies - "Probably not, but I can make sure you're not a part of it!" He finishes Doyle off with a shot to the head and retrieves the antidote, later using it to cure himself and Val of the mutagen as they sail away from the island.
Far Cry Instincts
In Far Cry Instincts, Doyle is a spy whose mission is to expose Dr. Krieger's experiments to the government. As Jack Carver tries to survive Colonel Richard Crowe's mercenary army, Doyle makes radio contact with Jack after Jack commandeers a headset. Doyle and Jack make a plan to regroup with Val Cortez so she can fly them out of the island and escape Crowe's men. Doyle maintains radio contact with Jack and provides Jack with intel he can use to survive the dangers of his missions.
Doyle later loses communications with Jack after Jack is taken by Crowe and injected with Dr. George Krieger's experimental serum which consequently gives Jack special abilities. After Jack escapes his confinement, he makes radio contact with Doyle again and discussed with him about the serum's effects on his body. Doyle tells Jack that Dr. Krieger has regulatory implants grafted onto his test subjects and they must surgically remove Jack's implant lest Krieger use its counter measures to kill Jack. While Jack went off to recover Val Cortez's pocket PC, Doyle set up a signal to mask Jack's implant device. However, Colonel Crowe's men have been trying to modify a microwave tower that will undo Doyle's interference signal. Thus, Doyle tasked Jack to reach the tower and destroy its hardware.
After completing their objective, Doyle directed Jack towards a research laboratory base. There Jack regroups with Doyle, Val Cortez, and a bribed Dr. Raditch in an operating room, where Doyle prepares Jack for the surgery. Doyle warns Jack that since the implant regulates his primal abilities, removing it may cause some unpredictable effects. When Jack woke up from the surgery however, he found himself beating a mercenary to death and sees he killed many people in a rampage. Furthermore, Val and Doyle are nowhere to be found and he must escape the base alive as Crowe and his men cause mayhem on the base.
Jack meets up with Val later on and they both make it into the security office of a mercenary base, where Dr. Krieger contacts them and tells them that Crowe had gone rogue and took Doyle captive. Jack then heads out to confront Crowe and recover Doyle. Eventually, Jack finds Doyle in an abandoned hospital in the wasteland carrying some sort of case. Doyle tells Jack that Crowe injected himself with the serum but overdosed, taking four times what Jack got and without an implant to regulate its effects. After revealing that Crowe went to kill Dr. Krieger, Jack and Doyle took a helicopter and headed off to the volcano where Krieger's lair resides but their helicopter gets hit with a missile.
Jack falls out of the helicopter into water but Doyle who was flying the helicopter crashes. Jack is able to infiltrate Krieger's base and is able to kill Crowe, followed by a confrontation with Dr. Krieger which resulted in the surviving abomination experiments turning on Krieger and killing him. Val manages to get a helicopter and extracts Jack moments before Krieger's lair explodes. Doyle who was rescued by Val beforehand, is on the helicopter with an injured leg; when Jack demands that Val and her agency owes him a new boat, Doyle remarked he had a better proposition. Doyle gives Jack a case that contains some unknown materials. During the game's ending, Jack is shown opening the case and laughing.
Far Cry Instincts: Evolution
Doyle is the CIA agent sent to get intel on the Micronesian rebel attacks and provide damage control for the escalating violence in Micronesia. After a Micronesian magistrate is murdered however, the entire region of Micronesia becomes in danger of destabilizing. Jack Carver meets Doyle again at Kade's safe house, where Doyle is interrogating Kade about why her lover murdered the Micronesian governor. Jack interrupts his interrogation and tells Doyle that he was framed for the murder. After Doyle vented his frustration about Jack's involvement with the situation, Doyle surmised that the native rebels were making their move after it is revealed that they were the perpetrators of the Micronesian magistrate's murder, and insists that Jack help him quell the rebels' takeover of the country. The 3 are attacked by pirates and forced to separate and move to a new location. Jack is able to find Doyle and Kade at the old shrine ruins, where Doyle is trying to restrain Kade and encourage her to leave Micronesia. After Kade argued Micronesia is her home, Doyle mocked her by saying she was smart enough to make any gutter her home. After Kade attempts to smack Doyle and flees indignantly, Doyle tells Jack that he can pacify the Micronesians for the murder of their magistrate if Jack helps him stop the rebel offensive.
Later that night, Doyle tasks Jack to find a rebel spy that the pirates kidnapped in a shanty town basement and interrogate him for information. After speaking with the rebel spy, Jack succeeds in finding out the location of a delivery truck full of weapons and supplies for the rebels, but Doyle informs Jack afterwards that Kade ran off and went missing. Jack finds Kade trying to sneak into a gated counter of one of the shanty town's facilities, but since Jack is being pursued by pirates, they are forced to run. Jack then escapes the town and meets up with Doyle after they burn down the suspension bridge in order to prevent further chase.
Doyle tells Jack that the rebels have taken the refinery and could use it as a launching pad for their conquest of the region. Doyle and Jack split up to find the truck so they could get past the road blocks. Doyle is later captured after Jack heads off and sees him being put into the back of the delivery truck, forcing Jack to quickly commandeer the truck and use it to ram the refinery gates so they can breach the refinery. Doyle meets Jack at the foreman's office and tells Jack to try and sabotage the refinery by flooding the drainage tunnels. While Jack accomplishes his mission, he finds Kade again hiding and she warns him that the Micronesian government doesn't trust in Doyle's ability to solve the issue and wants to bomb the refinery. Moments later, the two see helicopters doing bombing runs on the refinery, forcing them to run for their lives. Jack and Kade run through an underground area and regroup with Doyle, who is distrustful of Kade, but Jack is similarly suspicious of Doyle and questions why he'd want to flood the refinery if the Micronesian government was just going to bomb the place. Doyle explains that there are underground tunnels the rebels can retreat to that won't be penetrated by the bombs and if the rebels entrench themselves there, the army will never get them out. Jack and Doyle press on to finish flooding the drainage tunnels, but Doyle is ambushed by a rebel commando leader with a missile launcher and thrown out a window. Jack remains behind to fight the rebel leader with the missile launcher and escapes via an underground tunnel.
Jack finds an injured Doyle clinging on the dock by a mini boat and carries him on their escape raft. Doyle tells Jack that the channel they are on should be an exit to the outside and the two sail their way out through the underground river. Jack swims Doyle to shore and tells him not to move as he is suffering from broken bones, internal bleeding, and possibly a concussion. Moments later, a large group of rebels attack them but Jack manages to take them out. Doyle tells Jack to commandeer a boat from a nearby rebel camp and to escape but Jack refuses to leave Doyle to die. Doyle seems surprised that Jack cares about his life, but Jack claims he's only saving Doyle because he's the only one who knows how to escape their "hellhole". Jack tells Doyle to hide while he gets the vehicle but when Jack comes back with the boat, he sees Doyle is missing. Jack uses his primal sensing abilities to follow Doyle's blood traces but walks into a trap, where one of Semeru's enhanced warriors shoots a dart into his arm. Jack senses that the dart he was shot with was laced with something that temporarily neutralized his primal abilities and Jack is forced to fight the enhanced warriors in the jungle. After killing all hostile rebels, Jack finds a crashed plane wreckage with a working radio and a note (written in blood) by Doyle on the cockpit door so that Jack can reach him. Jack found that the signal was being jammed however, so Jack went get rid of the rebels' signal jamming transmitters, and ultimately located Doyle's emitter on a bridge just before he was attacked by a rebel helicopter.
Jack tracked Doyle's blood to a ruined temple where Jack finds Doyle dead at the temple steps with Kade's pendant lodged in his mouth. Doyle's death enrages Jack and compels Jack to go after Semeru inside the temple. Before Jack can enter the temple however, Semeru bursts through the temple gates and the two fight but Jack loses; culminating the battle with Semeru throwing Jack off a cliff. Jack manages to survive by grabbing onto a protruding branch and lessening the impact of his fall, but Jack still loses all his gear. Jack recovers his gear and finds Semeru again with his rebel guards at the outside of the temple, but he now has Kade and is holding her hostage. After Jack takes out the rebel guards and breaches the temple, Semeru taunts Jack by telling him that Doyle was weeping before he killed him and also called for Jack many times but he never came. Jack tells Semeru that even though Doyle was a snake, he was more of a man than Semeru will ever be. Jack tries to fight Semeru but once again is overpowered. As Semeru subdued Jack, he revealed his deal with Kade who double crossed Jack. Kade then stabs Jack with a knife laced with the neutralizing poison and Semeru drops him onto the lower floor.
Jack loses his powers for a short time and engages Semeru in a firefight. Semeru jumps through a hole in the wall and the two fight outside. Jack once again is able to use his powers and finally beats Semeru. Jack then kills Semeru by dropping him on a broken bamboo shaft protruding from some rubble. Jack sees Kade who tells him she's sorry for betraying him and said she had no choice as it was the only way for her to survive. Instead of killing her however, Jack gives her all the reward money since her selfish self preservation was such a human trait. Jack then kicks open the temple gates and escapes the base.
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