Sentinel is a 2003 limited series by Marvel Comics written by Sean McKeever.
Juston Seyfert is your average Midwestern American teenager, struggling with school, bullies, and family problems. However, his life changes forever when he accidentally re-activates an old Mark VI Sentinel in his father's junkyard. After fixing and reprogramming it, he opts to use it to try and scare his bullies at first — only to catch unwanted attention from the Commission on Superhuman Activities in the process.
A second Sentinel series was published in 2005. This one focused on Juston, still on the run after the events of the previous series, trying to hunt down his Missing Mom while also having to fight off government agents who want his Sentinel destroyed for their own ends.
Outside of their own series, Juston and the Sentinel have also made major appearances in Avengers Academy, Avengers Arena, and Sentinels.
Sentinel provides examples of the following tropes:
- All Love Is Unrequited: Juston's initial crush on Jessie is dashed by the revelation that she has a boyfriend already.
- Animesque: The series has an anime-inspired art style courtesy of Udon Studios.
- Betty and Veronica: After he becomes the town hero, Juston ends up as the Archie between Jessie (the Betty) and Ashleigh (the Veronica); the former is a genuine friend to him, the latter just wants to date him for the popularity. In the end, he doesn't end up with either, as Jessie has a boyfriend and he loses interest in Ashleigh.
- Bitch in Sheep's Clothing: Juston meets his maternal aunt when he's trying to track his mom down; she acts nice to him at first, but it's quickly revealed that she's a bitter woman who just wants his money. When he runs off, she promptly puts on the sheep's clothing again, pretending on the news that she's only concerned about his safety.
- Blackmail: The main antagonists of the second series are defeated when Juston threatens to expose their crimes (using video footage Sentinel has) if they don't leave him alone.
- Celebrity is Overrated: Juston becomes the town hero after he "stops" the Sentinel, but the novelty wears off incredibly fast for him, especially since he's guilty over what he did.
- Corrupted Character Copy: It's easy to see parallels between Juston Seyfert and Hogarth Hughes from The Iron Giant; both are kids with single parents who befriend a giant robot they find in a junkyard. However, thanks to his difficult upbringing and suffering bullying at school, Juston is initially a lot more selfish and short-sighted than Hogarth is, to the point that he uses the Sentinel to stage a Monster Protection Racket briefly. Likewise, the Sentinel is this to the titular Iron Giant; both are robots originally built for violence who end up befriending young boys, but the Sentinel has a much harder time shaking off its original programming than the Giant did. Downplayed as Juston regrets his actions and eventually works to make up for them, becoming a better person and overcoming his problems. While the Sentinel has a hard time overcoming his original programming, he genuinely tries to be better because of his friendship with Juston, and eventually, he succeeds. Juston Seyfert and the Sentinel, despite their flaws, are becoming more like the characters they are based on.
- Does This Remind You of Anything?: There's a lot of "bullied kid becomes school shooter" implications in regards to Juston's revenge plan. He even compares himself to the Columbine shooters when he expresses regret over it.
- Down in the Dumps: Juston's dad owns a junkyard, which is where Juston ends up finding the Sentinel.
- Dude, Not Funny!: While arguing with Juston over getting revenge on Josh and Greg, Matt accuses him of wanting to run away like his mom did, prompting an angry reaction from both Juston and his brother.
- Eating Lunch Alone: Juston opts to eat lunch in an empty classroom rather than face the chaos of the lunchroom without his friends by his side. He ends up meeting Jessie when she runs in to hide from a teacher.
- Fair-Weather Foe: Every kid who used to bully Juston suddenly wants to become his friend or date him after he "saves" the school. It's part of why Juston doesn't like talking about it.
- Fake Period Excuse: Jessie is introduced hiding in the classroom Juston's eating lunch in; she explains that she's been ditching class with a period excuse for the past two weeks because the teacher's a pervert, and he's finally catching on to her lying.
- Foreshadowing: The news reports shown after the Sentinel's "attack" show that the Commission on Superhuman Activities are looking into it, foreshadowing that they're gonna go after Juston.
- Groin Attack: At one point, Juston kicks Josh in the groin to escape him and his pals.
- Malicious Slander: In order to drive a wedge between Juston and Jessie, Josh and Greg spread a false rumor that he's been lying about her. It ends up working, and she wants nothing to do with him until she discovers the truth.
- Mirror Match: The main villains of the second series send another, more advanced Sentinel to destroy Juston's.
- Monster Protection Racket: Juston's first use of his Sentinel buddy is to run one so he can scare his bullies. He only does it once — partly because he feels guilty about it, especially the emotional trauma it caused, and partly because it got some unwanted attention on him from spooky government types.
- No Good Deed Goes Unpunished: Juston tries to save the survivors of a plane wreck with his Sentinel, but ends up outing its existence to the agents who are trying to find it in the process.
- Oblivious Guilt Slinging: After Juston "saves" his school from the Sentinel, Matt insists that he should have let the robot take out Josh and Greg first; Alex berates him for this and tells Juston he did the right thing. All this does is exacerbate the guilt Juston feels over faking the attack in the first place.
- Oh, Crap!: Juston's reaction when he finds out exactly what the Sentinel is.
- Prank Call: In retaliation for how she's trying to milk Juston's disappearance for popularity, Juston's friends prank call Ashleigh and pretend to interview her for Oprah, then record her answers and broadcast them on the school's P.A. system.
- Pyrrhic Victory: Juston succeeds in his plan to get the respect of his peers by faking an attack by his Sentinel, but it's offset by the immense amount of guilt he feels over it.
- Rage Breaking Point: After putting up with Josh and Greg's crap for much of the series, Juston finally snaps and initiates his Monster Protection Racket when they drive Jessie away from him and beat him up afterwards.
- Sequel Hook: The first volume ends with Juston taking the Sentinel from where it's locked up in the hopes that he can modify its tracking abilities to find his mom.
- Shout-Out: The relationship between Juston and the Sentinel is much like Hogarth Hughes and The Iron Giant.