Abernathy is a sweet southern boy, from North Carolina, who is trying to live without the shadow of his past haunting him. Various people in the Jeffersonian treated him badly upon learning of his criminal past but eventually treated him better upon learning that he just wants to put his past behind him and talk science in the lab, upon telling Hodgins this they eventually become friends even going as far as to tease each other. He has only got upset once, when Hodgins used the last of Finn's hot sauce that his deceased grandmother had made ignoring the note Finn had left stating it belonged to him and without realising that the hot sauce had sentimental value but forgave him after Hodgins used the lab equipment to discover the recipe and make more. He is a very honest person and has seen to have trouble lying, shown when his girlfriend, Michelle, visited him and requested he didn't tell her mother, Cam but he told Cam out anyway and tried to cover it up with Cam's help.
Finn had a criminal record with charges including joyriding, theft and attacking his stepfather with a hunting knife when he abused his mother and had spent some time in juvenile detention, but the record was expunged when he turned 18. Finn decided to quit, but he came back and received a warning from Brennan. After he returns to his work, Brennan asks him if his interest in forensic anthropology was related to a plan to kill his stepfather, which he answered yes to. She also asked him if he actually killed his stepfather, which he answered no to because after reading a paper she had published, he knew there was no possible way to cover up the murder if he had actually committed it.
In "A Bump in the Road", he begins a relationship with Camille Saroyan's daughter, Michelle Welton. Cam initially disapproves, causing Finn to back off out of respect for his boss's wishes, citing that he owed her a great deal for giving him a second chance and that since she is Michelle's mother, he has to respect her wishes. Cam soon relents upon realising they really want to date, and allowed the both of them to date. He attempts to lie when Michelle visits him without telling Cam she was coming but ends up blurting it out to Cam, Cam comes up with a plan where Finn would arrange to meet Michelle and then tell Cam where they were meeting so she could "accidently" stumble upon them, pretending not to have known Michelle was in town, afterwards Finn relents and tells Michelle about what happened but after he explained himself Michelle forgave him.
Finn originally doesn't get along with Jack Hodgins who teases him due to his southern accent and colloquialisms but Finn convinces him that as they both speak science they should focus on that not on what is different about them, Hodgins relents and they become friends after jointly making a snake vomit up evidence, even teasing each other in the form of nicknames, Hodgins calls Finn "Opie" and Finn calls Hodgins "Thurston". Finn does become angry at Hodgins one time when Hodgins used the last of Finn's hot sauce that his deceased grandmother had made, ignoring the note stating it belonged to Finn and without realising that it had large sentimental value but Finn forgave him after Hodgins used the lab equipment to discover the recipe using a swab from the bottle and make more, after getting Finn to taste it and make sure it tasted like the sauce his grandmother made, due to the nice taste the two decide to enter into business together, getting a chef on side to help make it and marketing it as "Opie and Thurston's Hot Sauce".