Joel has been described as a "violent thug, a brutal killer, and a torturer." He is shown to be able to kill his enemies with noteworthy brutality, earning his infamous reputation to those he encounters. During the aftermath of the epidemic that struck the country, he has resorted to working in black-market dealings and smuggling items or people of interest through quarantine zones or other designated areas. Because of this, he has accumulated valuable knowledge in regards to surviving the post-apocalyptic environment. Ellie notes that Joel has stained his hand with innocent blood when he reveals to her that he has been "on both sides", thus having the knowledge about a hunters' ambush and anticipating it. This dark past likely contributed to his experience as a hardened survivalist.
He also becomes extremely dedicated to Ellie, using any means possible to save her and keep her safe. He tortures several cannibals to find out Ellie's location, and then kills the other prisoner after he has gained information about Ellie's location. Ellie also cares greatly for Joel when she cares for him when he was injured, Just as Joel cared for her and protected her throughout their journey.
However, Joel's other side is also portrayed. Prior to the apocalypse, he worked hard to single-handedly raise his daughter. The outbreak and Sarah's death changed him into an apathetic, ruthless, and estranged man. He wears the watch that Sarah gave him the day before the initial infection broke out as a reminder. Upon meeting Ellie, he originally has a rocky relationship with her. However, Joel later grows to trust her and finds her reliable at most times such as Ellie spotting for Joel or providing support. As time passes, Joel establishes a father-daughter relationship with Ellie, reminding him of his beloved daughter, Sarah.
Whether being selfish, or not wanting to lose another 'daughter' to the whim of another again, he chose to save Ellie and try and start some semblance of a normal life again. It is speculated that his decision to massacre everyone inside the Fireflies facility in Salt Lake City is to cut all loose ends, to ensure that no one will have the knowledge of Ellie and thus no one will go after her in the future. In this sense he is the opposite of Marlene (leader of the Fireflies), who intends to sacrifice Ellie for a chance to save the rest of humanity.
Described as being in his late 40's, Joel knows what the world looked like before it was devastated. Over time, he has begun to become less bound by morality and more driven by doing whatever is necessary to survive. "What he wouldn't do in the past is almost a daily occurrence at this point," Bruce Straley, the game's director, notes.
Joel's character was a big inspiration when imagining my character's personality and traits.
Joel's character was a big inspiration when imagining my character's personality and traits.
