These are details about Jacob's friendships before and during the series.
Bevin is one of Jacob's close friends. Although the two never met in high school since Jacob graduated, they met when Jacob paid a visit to the school and got a job offer as assistant coach for the boys basketball team. Soon afterwards Jacob and Bevin became best friends after Jacob started working at Tree Hill High fulltime and Bevin felt really bad about Jacob's ex-wife cheating on him and promised him that he'll find a better wife that will love him which lead to her finding out about Jacob and Quinn's engagement. When Jacob was shot and in the hospital Bevin with the rest of the cheerleading squad came to visit him but Bevin gave him flowers and a card. After Jacob was released from the hospital Bevin was very happy Jacob made it and gave her friend a hug despite his injury.
Marvin 'Mouth' McFadden
Mouth is Jacob's closest friends in Tree Hill. After Jacob joined the NFL the two hardly kept in contact until Jacob had returned to Tree Hill after retiring from the NFL and sports in general. Mouth revealed he would watch every football game when he played for the Baltimore Ravens. While Jacob was in the hospital following a gunshot wound Mouth would visit his injured friend along with the rest of the current Tree Hill students including the cheerleaders and it changed Mouth in many ways.
Jacob and Peyton met through Brooke and they grew up as childhood friends despite Jacob being three years older then Peyton. As they grew up together as friends Jacob told Peyton that he has a disability and it made Peyton more concerned for her friend's well being especially when he is sensitive to fireworks and other types of loud sounds with the exception of loud music as he blasts his radio when he is working out. After Jacob left Tree Hill with his first wife Chelsea it broke Peyton's heart among the others but they kept in contact with each other through phone calls or texts and Peyton often would visit Jacob at his current home and bring Brooke with her to visit Jacob and stay a week of their summer with Jacob and Chelsea. While Jacob returned to Tree Hill after divorcing Chelsea he and Peyton had an emotional reunion. Peyton would later find out Jacob is extremely good at playing the guitar and so their friendship grew having find out they both like music a lot but Jacob is more of a classic rock and country music fan but it did not matter to Peyton as she does not care about what music her friend likes because she likes him for him. Half way through season one Jacob and Peyton hung out when Jacob was on break at the cafe and talked about him show casing his voice and guitar skills at open mic night at the high school. In a episode when Brooke and Peyton were feuding over Lucas Jacob did not defend either of the two girls.
Haley James Scott
(best friend and sister-in-law)
Haley James is Jacob's childhood best friend. Jacob has been friends with Haley since they met at the park in Tree Hill alongside Taylor and Quinn. Haley was the one who always supported Jacob even if he made dumb decisions at times but it was only because Jacob wanted to protect Haley from getting hurt and those who decided to pick on her. Haley felt shocked when she discovered that Jacob was in love with her older sister Quinn but Haley supported her best friend and tried her hardest to get them together. While Jacob was in high school Haley was only in junior high with his younger sister Brooke, but at that time Haley was never aware that Jacob and Brooke were brother and sister. Haley was very upset with Jacob when he started dating a cheerleader named Chelsea Mitchell who was a student at Tree Hill High and did not attend his wedding but later thought it was childish fighting with him so she tried calling him on his last day in Tree Hill to say her goodbyes but she later saw him come into the cafe to apologize to her for not marrying Quinn and she forgave him just when Haley started crying. Sometime during the start of Haley's junior year of high school Jacob returned home to Tree Hill he told Haley it was because he missed her the most along with his family and friends alongside the fact that Chelsea cheated on him and divorcing from her. When Haley was a child she grew attached to Jacob and notice he was the same way with her and her sisters. While Jacob was home in Tree Hill he saved Haley from being killed by a shooter inside Karen's Cafe but was shot in the process so Haley held a bleeding Jacob in her arms just before the ambulanced arrived though Haley's hands were covered in his blood. At the start of season two Jacob and Haley went on tour together after forming a band naming it Jaley. Haley later begged her parents to let her best friend move in with them because of problems at home regarding his parents threatening to kick him out for always taking Brooke's side. By the time Jacob had started dating Quinn Haley promised that she would take care of Jacob if something happened to him. While Haley was a junior she found out she was deeply in love with Jacob since they were kids and admitted to Lucas that she was jealous of Jacob and Quinn until she moved onto Nathan.
(best friend, co-worker)
Jacob and Lucas seem to be best friends but act more like brothers constantly having each others back. Jacob was an employee of Lucas' mother Karen at her cafe and then the two became closer and closer. Sometimes Jacob and Lucas worked alongside each other at Keith's body shop where they repaired cars together and sometimes Peyton's car when it breaks down. After Jacob graduated high school, got married and moved away Jacob and Lucas like Peyton kept in contact but Lucas mentions that he misses him and promised he would visit him. Years after Jacob returned home Lucas and Jacob worked take a trip down memory lane when Jacob works on his car at Keith's garage.
At first Jacob did not get along with Nathan because he was being a jerk to Lucas and even a worse boyfriend to Peyton and warned Nathan if he does anything to either Lucas he would not hesitate to hurt him. Jacob later sees that Nathan is trying to change for him but would not believe Nathan. On the day of the shooting inside the cafe Nathan watched the news and was horrified after the events that occured and rushed to the hospital to find out Jacob's condition. Once Jacob out of the the hospital he was forced to take administrative leave, but Nathan refuses to someone he truly cares about alone in his house so he urges Whitey to let him help the team win the game that same night though Whitey refuses to allow that to happen after what Jacob's has been through since the shooting. Nathan also believes Jacob is hardheaded at times because he is tough on him and that was only because Jacob does not want Nathan to turn out like Dan. Jacob and Nathan later apologize to each other after their fight and the two become friends. At first Nathan believed Jacob was in love with Peyton or Haley but later sees that Jacob is in love with Quinn Haley's older sister.
(best friend, older sister-in-law)
Meeting at the park Jacob and Taylor became best friends and acted more like siblings compared to Taylor's sisters, but Taylor was aware Jacob lhad feelings for Quinn. Taylor is much older then Jacob by two years but it would appear that Taylor cares for Jacob like a brother growing almost attached to him. Sometime Jacob and Taylor drifted apart when Jacob graduated and moved away after marrying his first wife Chelsea but Jacob would later see Taylor at an autograph signing while Jacob was in the NFL and he was also giving away some of men and women sizes of his jersey and he gave one to Taylor a present. After Jacob returned home to Tree Hill Taylor was never aware until the news leaked of the shooting and visited him in the hospital afterwards to show her friend support and spent the night with him along with Quinn and Haley. It is shown that Jacob cares a lot about Taylor and is afraid something will happen to her. In season three Taylor was the first to learn about Jacob and Quinn's engagement and was extremely happy for them.
(best friend, wife)
Quinn is Jacob's childhood best friend and wife. Jacob met Quinn at the park and it sparked an interest for each other. Quinn was always nice to Jacob and never had a reason to be mean to him not even after learning about his disability. Jacob defended Quinn's honor throughout elementary school because of bullies who picked on both of them and eventually had enough and fought them in a three on one fight which Jacob won after hitting their bullies multiple times in the face almost killing them but stopped afterwards. Soon after Jacob was suspended he was not able to see Quinn because he was grounded and that was the only time he was ever in trouble at school. Since then Quinn realized she was deeply in love with Jacob since she was a kid. By the time the duo begun high school things got a little messy when Jacob started to date a cheerleader named Chelsea and it caused a huge fight between Quinn and Chelsea. Quinn tried to stay strong for her best friend but it still destroyed her in the end even after Jacob married Chelsea which felt like an insult to injury to Quinn but she knows that Jacob would never do anything to hurt her but Chelsea would. While Jacob was living in Baltimore, Maryland he and Quinn kept in contact with each other but soon after Chelsea found it she took Jacob's phone away from him and banned him from speaking to Quinn. Quinn was never aware of how bad Jacob's marriage was with Chelsea and later decided if he divorced Chelsea she and David would let him stay with them but David did not think it was a good idea because he knows of Quinn's feelings for Jacob so he let Quinn go so she could be with Jacob and chose to remain friends. At the start of season two Jacob and Quinn attend their high school reunion were Jacob proposed to Quinn after a year with her and decided their wedding would be held over the summer.
When Jacob met Rachel she was really sweet and nice to Jacob because she believes he is a sweet person who loves everyone in Tree Hill with the exception of Dan Scott. Rachel has protected Jacob and took a bullet for him
during the school shooting in season three which caused Jacob to relive deja vu since he was shot two seasons prior and was not about to let Rachel die on his watch. The episode set hours after the shooting Quinn saw that Jacob thought of Rachel as a little sister much how he felt about Haley. Brooke even saw that Rachel changed Jacob as she helped him with his anger alongside her and Quinn. After Rachel woke up from her coma she called Jacob "big brother" as if they were related. Eventually after Jacob had a daughter with Quinn he named his daughter after Rachel because of how kind Rachel was to him and he wanted to repay her by naming his daughter after her. Jacob later learned Rachel was abusing drugs and tried to help her fight it because he doesn't not like that Rachel and wants to old caring and really sweet Rachel back since that is the Rachel he cares about. Rachel trusts Jacob to protect her when she is in trouble and needs help.