Oh they were both doomed from the start.
Blykes "Everything will be fine" mentality was the key on what led to his imprisonment, because for them, that's exactly the way it's always been. All 3 of them have gone through more numerous death situations than anyone else in the series, and yet despite being exposed to the reality if their world, they still hold hope. Despite knowing the numerous deaths the authorities drop in order to prevent vigilantes and the era of peace, they still fight and stand for what they believe in. Instead for worrying of themselves and the stakes they're currently going through, they continue forward for the people they see need their help. They live selflessly in a setting where its preferred to live in a way for only yourself. Its exactly this what makes the remi-blyke-and-isen trio so distinct from the rest of the characters. In a world where the selfish strive, the selfless have no place. And here comes Arlo.
From the beginning Arlo was always seen as an arrogant selfish bastard who cared for the order of the hierarchy and control. It's the exact reason on why he attacked John in the first place. Midway through out the story, Arlo is exposed the terrors and reality of the world they live in, processing it in a different approach: denial. It's during this time where Arlo starts to see situations from a different perspective, using Remi, Seraphina, and John's situations as a way for him to understand. He begins to show more of his selflessness in an environment (the Bureau) where only the powerfully and selfish thrive upon in, putting himself at risk. It's been stated multiple times the actions Arlo takes in order to cover for the main 5 can easily get him arrested and stripped from his position, and yet he continues to do so anyways. The change in Arlo was something dramatic and critical to the story, as it changed his environments view of the ways he ruled before, to his act now (ex: elaine, zeeke, isen, cece, JOHN, SERAPHINA). The moment he realized he was living more selflessly, he always reminded himself of the consequences his actions will lead to. Because he himself doesn't want to live this way. And he has said it multiple times as well.
These 2 moments where what set in stone both of their imprisonment. The selfless once again committing an act in order to save another, and the "selfish" going against his own ideals in order to protect those he cares for.
Blyke litteraly had an opportunity to get out. To leave, to live another day once again. And yet a simple act in the moment in order to save someone in need was the result of his abandonment and imprisonment (not blaming isen and remi for this they genuinely had to choice).
And the same goes for Arlo. Despite being the oldest out of the main 6, he's still just a kid in highschool. Throughout the entire 2nd season, all he wanted was to graduate. The moment he uttered the words he was going to kill fury, it was clear he was going through mental crisis. The most composed and well kept character in the entire series was going to be the first one to commit murder from the main characters. And the thing is, it really was no surprise who couldn't do it. That's the contrast between him and John. Both going through mental and identity crisis and similar approaches, yet having different results (but that's for another day). If he did succeed is murdering the very obstacle in a moment that will probably never repeat again, they both could've escaped. But how can an unstable kid commit murder? The best scenario was not killing fury. Because even if all 5 of them got away, fury wouldn't be the only one who was killed that day. Arlo as a person would've died as well. People often forget Arlo is not John, they do not share the same mentality. (And the thing is no matter what John says, he wouldn't have been okay either if he did succeed in killing all the Bureau.)
Which leads us to now. I think it's interesting how the selfless and selfish characters where the ones taken captive in different environments, despite both committing the same crimes on the day of their capture. Because then again, who's the stronger one out of the 2?
