My character's backstory: Too tragic/unbelievable/ridiculous?

I'm coming up with an idea for a webcomic, and I want to know if my character's backstory is good or bad. It's not very likely that I'll draw it, but I want it to be good anyway.

The world is Mundane Fantastic, and about a quarter of the population has some kind of magic. The main character, Jonathan, was fourteen and on a flight home from vacation with his family. A magical disturbance of some kind forced the plane to crash-land in the mountains. Once it was clear that everybody was safe, people started to retrieve their things from the crash. Jonathan volunteered to get a pretty girl's luggage, because he's fourteen and she was basically a Hello Nurse. However, while in the plane, a demonic figure teleported in and started attacking some of the people in the wreck. Jonathan panicked, retrieved his father's hunting rifle from their luggage, and attempted to shoot it. He wounded it, but he was captured by another figure and brought to a prison.

He was kept there for about a year. The disturbance had been caused by a small group of demons who had been building power for some time, partly by giving power to those who would serve them. One of their lieutenants had been the one Jonathan shot, and he was a pissed off, vengeful Jerkass. While Jonathan was there, the lieutenant and his "colleagues" tortured Jonathan in revenge, both physically and mentally. Part of what they did to him involved embedding magic spines in his arm; these spines ensured that all Jonathan's injuries would be healed in four hours, but caused him constant pain, and could not be removed without his torturers' intent, which wasn't happening. Over this year, the demons took over the world and set up an evil empire.

Eventually, Jonathan was released, but the spines weren't removed. He was put in a mental institution for intense therapy for his severe post-traumatic stress disorder, and over several years, slowly got over the worst of it, but he still had bad dreams and the spines in his arm. By this time, he was eighteen, so he joined a resistance force to try to drive the demons out. Over the years, he gained experience in firearms, driving, munitions, and got acquainted with hacking.

However, the entire resistance group was a ploy by the demons to gather all their enemies in one place. They assaulted the group's base and killed the majority of the rebels. Jonathan escaped, took a portion of the resistance's finances, and set on a Roaring Rampage of Revenge by himself. The story starts when he's twenty-six.

Apologies for the Wall of Text.

It sounds like all his misery logically follows on prior events, so there's no confluence of coincidences (which is necessary for Deus Angst Machina). You'd have to write him as a severely traumatized person, which can be tricky if you don't have a good understanding of trauma, but his backstory certainly wouldn't break Willing Suspension of Disbelief just by being so miserable.

I was planning on writing him traumatized anyway - he starts off still having nightmares and not having much else besides his revenge, for starters. I was also planning on including minor details - for example, in the prison, deep-sounding bells mark the start of every day, so for him, they mean the start of torture again, even ten years later. There's one part where he hears a deep bell at a party and has a panic attack. Additionally, when recounting his story to someone else, he breaks down and starts sobbing. He basically has to force himself to keep telling it.

The character's backstory does not concern me as much as your world-building. There seem to be, let's say, multiple points I have trouble comprehending.

• The crash. The fact that everyone survives the crash-landing and was retrieving their stuffs is all well and good, if slightly unbelievable. It was when the protagonist volunteered to fetch the girl's stuffs that I begin to raise my eyebrows. Where is his parents? Wouldn't they object to his son, you know, traveling back into a wreckage that could blow up any moment to retrieve a stranger's gear?
• A small group of demons, some of the higher-ranking NC Os are weak enough to be injured by a hunting rifle managed to take over the world that probably has an armed force comprised of at least one forth magic users. Unless you make it absolutely clear they have some sort of bigger bros from the great beyond of Cthulhu's maginitude this is not happening.
• There is one thing called kicking the dog, and there is another called paying special attention to tormenting one who does not warrant it. From the way I understand Chaotic Evil individuals, the punishment for injuring them in self-defense is usually quick (though painful) death. A Fate Worse than Death is only reserved to those who had wronged them in the past so much they don't deserve to die. So by having the demons torture your guy to such a magnitude, you are unintentionally making him 'special' without warrant.

These are my main peeves with your plan. In this way, it sounds almost as though the demons are rearing this character to be the one to destroy them in the end. Almost.

I am sorry if I misread anything, but the way this story goes... no, I don't think it will work well. Again, apologies for my bluntness.

1. I'm too much of a nice guy to kill nameless people off so early. I need to get over that. As for the crash, I just realized that if I swapped the "rebellion" and "prison" parts of the story, not only would everything make a lot more sense, but this part could be removed from the story; see more below.

2. I really should've been clearer; the figure he injured was one of the people who made a Deal with the Devil; the actual demons are the big bros. Jonathan's revenge is against the ones who sold their souls.

3. As mentioned above, I could make him get captured when the demons break up the resistance. That way, all the rebels could be captured, so it wouldn't look like he was being singled out. He could just join at eighteen after a normal life, interrupted at fourteen by demons taking over the world.

4. No apologies needed for bluntness; it made everything clearer.

Yep, that makes much more sense. Although you might want to clarify exactly on how powerful the demons are. I mean, for them to succeed that easily given that the world never really lacks heroes means they have to be ridiculously powerful...

I'm still not sure how powerful the actual demons are, but they've been gathering power behind the scenes for a while now, so maybe a takeover could be relatively quick. Or maybe not. And there are also plenty who would make deals with devils.

Glad to hear it makes sense to you. It also makes more sense to me.