Agent Michael "Mike" Emerson Weston is one of the main supporting protagonists and an FBI agent. He was one of the few people in the FBI who knows where Claire Matthews was in protective custody during Joe Carrol's master plans. He is Ryan's right handed through out season 1 and is replaced by Max Hardy in season 2, but later returns as his partner again, along side Max, as the two appear to be developing into a relationship.
Mike is a very tech savvy guy, who is also a fan of Ryan Hardy. He studied behavioral science at Wesleyan; his dissertation was about Carroll (however he mistook Carroll's killing spree at Winslow for sexual arousal rather than the insanity of art). He has been with the FBI for three years and is the youngest of his unit. It has also been mentioned that he spent two years working for the FBI's witness protection unit.
At first, Ryan has very little respect for Mike. However, in Mad Love, he trusts Mike to save him from Maggie. After Mike does that, he starts showing respect for Mike, and Mike becomes his right-hand man, like Roderick is Joe Carrolls right-hand man.
In "The Fall", Weston is shot in the chest by a follower, although the specific follower knows he is wearing a bullet proof vest. Leading to doubt about Weston's position from the older officers, he goes back to his room frustrated, however, Joe's followers are there and kidnap him to a remote location. He then meets Roderick, Joe's right hand man who goes on to reveal a lot of information about Mike they know about him. He demands Claire's location, to which Mike says he doesn't know. Roderick then tells him to play their "game" and it gets more intense as Mike is forced to fight Charlie in a fist fight, then with a pipe having broken bones afterwards. He gives Mike one last chance, but Mike refuses, still saying he doesn't know. Roderick tells Mike that he believes him then has Charlie stab him. Just as the others try to kill him, Ryan and Debra arrive and shoot several followers as Mike falls unconscious from his wounds. He is hospitalized and it is revealed to Ryan by Debra that Mike not only did know Claire's location, but he was the only one who did and refused to tell anyone. Ryan looks at his unconscious body with depression and frustration over what Joe's men did to him.
In "The Curse" Mike finally returns albeit with his injuries not fully healed and is clearly having an impact from almost dying. His appearance becomes more rugged with facial hair and bandages on his head. He assists in taking down the militia home of Joe's and finding a militant leader named Daniel, the person who gave Joe that home. Once arriving, Mike breaks open the window and brutally attacks Daniel who tried to shoot them till Debra stops him. Ryan tries to talk with him, but Mike keeps saying he's alright. However, Joe and Jacob appear at the house as well and Joe ties Mike up while pressing on his wounds for fun mocking Ryan as Mike tells Ryan to kill Joe, but the glass is bullet proof. Ryan reassures Mike that he won't kill him since Joe needs him to get out alive. After Jacob arrives downstairs with Debra, he leaves with Joe and make an escape. While in an ambulance, Mike finally admits he's been very angry and tense over what happened and apologizes over the whole thing, to which Ryan says he's fine and is told to get better.
After being checked out, Mike returns and is shocked to see Roderick at the police station and tries to stop him, but the other police officers stop him before he has a chance to tail him. After they catch Roderick, Ryan forces him to take him to Joey (who he kidnapped as insurance) while Mike was in the trunk following them. Roderick is then killed by Joe's followers at the location and Mike takes Joey upstairs to hide him and begins a fight with a follower and kills him with his gun. However, Jacob took Joey away as Ryan went after him. Luckily, Jacob finally did the right thing and let Joey go with Ryan. Back at the station, a follower named Melissa comes forward claiming she wishes to do the right thing, but uses this moment to stab Nick in his eye resulting in Ryan and Mike shooting her dead.
After Debra is abducted, Ryan and Mike follow the location Debra can describe with her phone. At the location, Mike is almost killed by the follower Alex, to which Ryan captures him. Demanding Debra's location, Ryan and Mike brutally torcher him for her location to which Alex gives in. However, the duo arrive too late as Debra died before they reached her. While Mike mourned her death, Ryan, filled with rage at Alex's taunts, murders him in cold blood. After finding Joe's finished manuscript, Mike and Ryan discover Joe planned the whole thing and that Debra was supposed to die. But Mike notes so was he and that they can change the ending. Though Ryan says he doesn't know where to go, Mike easily sees through his lies, but is unable to stop him and is left behind.
After Ryan's fight with Joe, Mike informs them of Joe's death, to which he seems uneasy about and hands Claire a phone to talk with her son. After Ryan and Claire are almost killed by Molly, a tearful Mike informs Ryan of Claire's death (which is later a lie as Mike had put her in protective custody for both their sake).
A year after Joe's death, Mike is back living at home. However, after hearing of the subway massacre's, Mike, along with Ryan, are recruited again in the FBI on board to assist in gaining information on the identity and motives of the attackers. Ryan dismisses the FBI's request for his help and appears to want nothing to do with the situation, much to Mike's disappointment. However, Mike followed Ryan back to his apartment and discovers Ryan's vigilantly activities of chasing Carlos Perez, which Mike is forced to confiscate his belongings so Ryan won't be arrested. At the same time Ryan finally reveals info on the belief that Joe may be alive, revealing that Joe had a half-brother and that his brother's body may have been used to fake his death. Mike however, dismisses all of this and tells Ryan to either stay out of the FBI's way or give them his help. at this time he meets Max Hardy, Ryan's niece, to which they do not meet on good terms, to which Max mentions that Mike should take it easy on her Uncle.
After discovering Emma Hill's location, Mike and agent Gina Mendez storm her home and kill 6 followers and take the remaining one to custody. Ryan was present, but Mike says he'll tell him what happened later. However, after Ryan asks for his help on Lily Gray, the only survivor of the subway massacre, they soon discovers her in a lie and with the help of Weston's subway video footage realizes that Lily is involved with the cult. She escapes after murdering two agents, to which Ryan and Mike reveal her involvement to the public.
After discovering surveillance of the missing Mandy Lang, Weston, Mendez, and the FBI discover an image of Joe and Mandy from a surveillance camera, but fail to actually identify the man in the picture as Joe, however, Mike has doubts. Believing Ryan may be right, he receives a call from Ryan about the location of Lily's home, to which Mike is unable to tell Mendez, as he now believes the FBI may be compromised. Mike travels to Ryan and Max's location on his own. Revealing the image to Ryan, they confirm it is Joe Carroll, alive. Mike apologizes to Ryan for not believing him earlier and the create a plan to lure Joe out. The plan works as they capture Luke Gray. However, Mike's erratic behavior causes him to rough Luke up after the latter taunts him and what he would do to Max. While Ryan goes to Lily's house, Max and Mike are at the exchange for Joe, to which Lily never kept her word and brought a hostage instead. After Mike flattens her tires, he threatens to kill Luke after stabbing him twice in the back with a box knife. He begrudgingly lets him go when Lily lets her hostage go and they give chase. When Mike finds Lily and Mark, he is ambushed by Luke, to which he shoots him twice in the chest (though Luke was wearing a bullet proof vest). Just as Luke stops him from going after the others, Mike beats him to the ground and brutally beats him to a bloody pulp to the point of almost killing him had Max not stopped him. They then meet Ryan at an airstrip just missing Joe, as the group now realize Joe is really alive. Ryan, Max, and Weston conclude that somebody from the FBI must be compromised and feeding Joe information.
After Weston's outburst on Luke, Weston leaves the FBI building to go home because he feels mentally unstable after assaulting Luke. After hearing of Max's capture, Weston returns to help find Max. After Ryan receives the video of Max on his phone, he questions Luke, who remains in custody at a hospital. Luke reveals the man's name: Kurt (Bowlen), known as "The Huntsman" - a known serial killer. The FBI find Kurt's home; Ryan and Weston handcuff his son until he reveals where his father is. Max escapes into the woods, with Kurt chasing her. FBI police dogs track them down and Weston finds Max right before Kurt is shot dead by Ryan. Julia gives Joe a lie detector test to ensure his intentions are genuine. Back at the headquarters, Ryan receives a video text message from Lily and puts it on screen in the FBI's office. Weston recognizes Lily is at his father's house, as the video turns to his father strapped in a chair. Mark slits his throat and kills him. As Weston runs out of the room crying hysterically, Lily teases Ryan that she has more surprises in store for him. Ryan catches Weston weeping outside and holds him.
The funeral for Weston's father takes place, with Ryan and Max attending. When Ryan goes missing, Mike and Max go to find him at Dr. Arthur Strauss's home. Weston finds Arthur's pupil Cole as Cole was looking for tools and shoots him. Ryan frees himself and then Carrie Cooke. Ryan and Weston tie Strauss to the table and whip his hand until he reveals that Joe had a connection to a female in the FBI. That night Mike and Max begin to bond as she asks how he's been since his fathers death, and Mike seems to now start opening up to him since then. After he fells asleep, Max was seen watching over him.
After Max has an embarrassing moment of her almost catching Mike naked, Max and Weston narrow their list of possible moles in the FBI, a list including Agent Mendez. Ryan doesn't believe she's guilty, but questions her outside of her apartment. After questioning Mendez, Ryan and Weston track Mendez as she travels to Jana's house. Luckily, Jana's friend lets Mike and Ryan in. They find Mendez and have an ambulance called before cornering Jana and questioning her about where Joe is. Jana proceeds to shoot herself in the head. Mendez is taken away, alive, in an ambulance. After the massacre at the book store, Mike was present watching Carrie plays the clip on her news report, a video of Joe announcing to the world that he's still alive and nobody is to feel safe. Weston walks Max out and ends up getting into a car with unknown men. Weston is transferred to another car and blindfolded on the way to a location where he meets up with Agent Philips. Philips brings him to a room where he comes face-to-face with Claire Matthews, alive with a new look.
- Has three brothers; one he is close to, the other two he hates. (Mad Love)
- He is the second-youngest member of his FBI unit.
- He has a terrier mix.
- He carries a Glock 22 as his FBI issued sidearm.
- After the events of "Welcome Home", he seems unafraid of crossing boundaries and abusing Caught Followers.
- He is from San Diego, California.
- His first and last name - Mike Weston - is similar to that of Michael Westen, the main character of TV series Burn Notice.