The show's over-arching themes:Arc Words:
Originally spoken by Reese to Jessica in the airport flashback (where it also doubles as Foreshadowing of Jessica's fate); various references to "going it alone" or "you're all alone out here" appear in several episodes (e.g. the Iraq flashbacks in "Get Carter").
The counterpoint to the above, first used by Finch while trying to convince Theresa not to run away again; seems to show up at least once an episode. Culminates in the discussion of trust between Reese, Carter, and Fusco in "Firewall":
Reese: Trust is complicated, Lionel. For example, I'm sitting in a police car with one cop who tried to murder me and another who spent six months trying to lock me up. So you'll forgive me if I take things one step at a time.
There's another counterpoint which is repeated frequently (e.g., Reese to Carter in "Get Carter," to Maxine in "Bury the Lede"):
This becomes extremely important in "Endgame".pilot episode:
All of the main characters have lost someone close to them:
- Reese lost Jessica (the voiceover is what he says to her killer when he confronts him in "Many Happy Returns")
- Finch lost Grace and Nathan when the latter was killed in a government-orchestrated staged terrorist bombing and he had to fake his death and loss of his body to keep the former out of harm's way.
- Carter's marriage failed when her husband came back from the Middle East with PTSD (revealed in "Endgame")
- Fusco is divorced (under circumstances never fully explained)
- Shaw lost her father at age ten ("Razgovor") and her partner Cole ("Relevance")
- Root's Start of Darkness was triggered by the loss of her best friend as a child.
It's true of many of the POIs as well: Elias' entire life before the series has been one complex exercise in avenging the loss of his mother. Numbers such as Dr. Tillman in "Cura te Ipsum" and Darren in "Wolf and Cub" are seeking revenge against someone who took a loved one away from them. Other numbers, such as Wayne Kruger in "Nothing to Hide" are on the receiving end of revenge.
The theme is also present in The Machine. It's "a system of unimaginable power" built to fight monsters, but it seems to have turned the people in the government who control it a little monstrous themselves:
Many episodes also question the morality and utility of vigilante action:
Finch offers Reese a second chance at life; Reese and Finch's interventions give many of the POIs a second chance; Fusco tries to take advantage of the opportunity for one which Reese unintentionally extends to him. In Fusco's case, his continuing association with Reese and Carter leads to his redemption, as he explains to Simmons in "The Devil's Share":