Jacob was born to a successful doctor in Lake Whitehurst, Jacob didn't want to become one himself. He dropped out of medical school, and was persuaded to join Joe's cult. It was suggested in The Curse that he has a difficult relationship with his father.
Jacob is one of Joe's most long-term Followers, though unlike many of the others, he hadn't killed anyone when joining them. During meetings with the other Followers, he claimed to have killed a girl while he was in high school and dumped her body in the ocean. He told Joe the truth early, but Joe was okay with it and agreed to keep it secret, saying he would commit his first kill when he was ready. He met Emma when she visited Joe in prison and was set up on a blind date with him. He later witnessed her killing her mother and helped her get rid of the body.
Over time, he formed a bond with Paul, a recent new follower who eventually discovered of Jacob's inability to kill. He promised Jacob he wouldn't tell anyone on the condition he return the favor someday. They later were assigned to keep track on Sarah Fuller, Joe's last victim, and act gay for her to gain her trust. Unknowingly, Jacob was torn for his feelings with Emma and his friendship with Paul due to Paul seemingly gaining real feelings for him.
Living under the alias of Will Wilson and pretending to be the gay partner of "Billy Thomas," Jacob and Paul surveilled Sarah Fuller for over 3 years. Gaining her trust, they waited for Carroll's escape and delivered Fuller to him, so he could finish his "work." It has been suggested various times that due to the act that Jacob and Paul put on Jacob became bi-sexual since he has feelings for both Emma and Paul although he refuses to admit it.
Afterwards, Paul, Jacob and Emma kidnapped Carroll's son, Joey, under Carroll's commands. ("Pilot") At the house in the country where they are keeping Joey, he and his girlfriend, Emma show affection towards one another, much to the dismay and jealousy of Paul. The two share a room in the country house, and Paul walks in on them making love. ("Chapter Two")
Despite all of this Jacob tried to be the mediator between Emma and Paul since at first they did not get along. Jacob continues to try to control the problem when in a fit of rage and tired of being considered the third wheel Paul brings home a kidnapped girl known as Megan Leeds from a convenience store in The Poet's Fire
In (Mad Love) Paul eventually tells Jacob's secret which is the fact that Jacob lied about being a murderer to Emma Hill, only telling Joe Carroll and Paul about it. Emma responds by teaming up with Paul and trying to get Jacob to kill Megan Leeds as his first but he was unable to do so even when she was tied up. Later he lets her go only to have her be recaptured by Paul and Emma. Jacob later confronts Emma and Paul in the shower and tells him that he is sorry. They tell him they aren't giving up on him and hug him in the shower.
At the beginning of The Siege he wakes up in bed with Paul and Emma as a result of the shower scene from the previous episode. When he goes downstairs he catches Joey using the phone and pulls him away. He freaks out and later helps the search for Joey with Emma and Paul. Once they find him they meet Hank Flynn and begin to pack up the car; when they find Hank gone they split up and search for him.
Jacob is seen in the next episode The Fall which immediately follows the events of The Siege. Once he realizes they have Ryan Hardy, Joey Matthews and Megan Leeds trapped with the F.B.I. surrounding the place they begin to freak out whether they show it or not. Emma escapes the house with Joey leaving Jacob and Paul behind and in the confusion Ryan breaks free and stabs Paul. He rushes out of the house leaving Jacob and Paul for the F.B.I. Paul tells Jacob to escape but he refuses to leave Paul's side. Luckily for them Roderick who is the reason Emma escaped, sent two men disguised as SWAT into the house and got them both out safely. Jacob stopped a man's car; beat him up and threw him out and he then helps Paul into the car stating they will get him help. Paul thanks him for not leaving him to die and Jacob swears he will save him. As Emma parks the car for a moment she answers a call from Jacob who is crying; demanding to know why she left them; she tearfully hangs up the phone without a word.
Jacob and Paul are mentioned by Joey in the beginning of Let Me Go but not seen and at this time they are MIA. It is stated in Welcome Home that they are still missing but Joe thinks them to be safe as Emma has not seen anything on the news about their capture or deaths. This however was a lie, as Roderick pointed out Emma's phone is filled with messages from Jacob, but she has yet to listen to even one.
Jacob reappears at his parents' lake house near Arrowhead Lake, Pennsylvania and meets his mother, who shows fear towards her own son about the recent events he's done. She tries to reason wit him that he's done a lot of bad things and wants to help him, but begs him to open to her. After she looks over Paul's condition, she mentions Paul will die unless he gets him to a hospital. After finding Joe's location, Jacob tries to get Paul to go with him, but Paul knows he has little time and begs Jacob to kill him so he can fulfill his promise to him. Despite Jacob's hesitance over killing his best friend, Paul believes in him and declares his love for Jacob as a tearful Jacob smothers Paul with a pillow as his first kill because Paul wanted his death to mean something. After Paul dies, Jacob lightly kisses him on the head and later reunites with Emma seeming to have a whole new outlook on things in Love Hurts.
His reunion with her becomes very sour, after reuniting with Joey and Joe he gives Emma the cold shoulder. Joe asks of him to give Emma a chance despite that what she did caused Paul to die, but reluctantly agrees. As they talk, she tries to tell him Roderick left her no choice and believes Jacob would have done the same, but he states he'd never do such a thing. Later that night, Emma tries to reason with him that she loves him, which leads them to almost have sex till Jacob keeps seeing images of Paul over him telling him to kill Emma and that she can't be trusted. After "killing" Paul, Jacob, now completely different from before, holds Emma in his arms telling her about what she did caused Paul to die and that he had to kill his best friend because of her. He grabs her neck and threatens her stating she should watch her back from now on. Currently, Jacob has no idea that Emma willingly slept with Joe.
In the episode "Whips & Regret," Jacob tells Emma that the Jacob she loves is dead and that he is a brand new man. Since then Jacob now acts much more aggressive and serious, going as far as to throw Claire to the ground stating that he's been ordered to put her in her place for Joe less she refuse. She says if she wants to see Joey, she'll have to "make an effort". She does so as she has dinner with Joe that night.
After the bunker is found, Joe takes Jacob and Vincent to Daniel Monroe's home and Jacob kills Brian Fowler and takes Debra Parker hostage. As she tries to talk with him about his life and why he's doing this, he refuses to listen even after how he has a golden life. Jacob uses her as leverage to force Ryan to let Joe go in the basement. Later at night, Jacob watches the news as he's on the TV about his choices in life leading him to call his father. His father begs him to tell him where he is, but Jacob hangs up and starts crying instead.
The next morning, he informs Joe about Ryan on the news about the deal he'll give one of Joe's followers if they turn themselves in. Joe tries to persuade them that they aren't in trouble and Ryan is desperate, but Jacob sees more to that. After Roderick kidnaps Joey, Jacob offers to find him with two others and stay outside Ryan's work place. They follow them to Roderick's base and kill him. After Ethan and Michael are killed, Jacob finds Joey and tells him to be quiet and tries to take him back to Joe. As they run, Joey begs him to stop stating his mom says he's one of the bad guys, but he says that's crazy. Ryan keeps him behind a shed and Jacob yells he has to take him back to Joe, but Ryan tells him Joe doesn't care about him or if he dies, causing Jacob to question everything he's doing. Ryan continues to persuade him to let Joey go which, with tears in his eyes, and Joey tearfully begging also, Jacob finally does the right thing and lets Joey go, but escapes in the process. At home, he is greeted by Emma, to which he begins to realize they are all going to die soon.
Jacob dies by his throat being slashed by Emma.
- Ryan Hardy (held hostage at gunpoint; escaped)
- Megan Leeds (threatened to kill; relented)
- Paul Torres (suffocated with a pillow on his request)
- The attack at the Monroe house:
- Brian Fowler (slashed his throat)
- Debra Parker (assaulted; held hostage; threatened to kill at gunpoint; was released)
- Tim Nelson (shot to death with Michael and Ethan)
- Jacob is the second main character who kills another main character.
- Jacob is currently the only one of Joe's followers to have some good will in him, what with his regret on his decision to follow Joe and allowing Joey to go free.