Being stuck between the honorable elder brother Diego and the impressionable younger brother Stefan, Jonus does his best to strike out on his own. Like Diego, he is very ambitious, but not as caring and very opportunistic, which leads to a certain reckless and narcissistic behavior, though this tends to suit him.
During the opening cinematic, he is a member of a Rimtech survey team whom his brother Stefan is also a member of, while the eldest brother Diego commands. After a battle with a Hedoth Combot, an unfortunate bombing run by Mil-Agro that knocks Stefan off a cliff, and the discovery of an alien arm by Jonus himself, he defects to Neuropa with the high-priced piece of technology. This systematically ignites a war between the three primary corpo-nations, Rimtech, Mil-Agro, and Neuropa, and thus the campaign of Metal Fatigue begins.
As the player progress' through each campaign, a log from each brother is kept. The following is an excerpt from Jonus' personal "testament" that appears in-game during the events of the third campaign. Each entry is prefaced with a reference to "The Divine Order of Neuropa" of which Jonus is a "Brother", along with the number of years and days since the "Enlightenment".
Y: 64 / D: 358
Well, here I am, at Neuropa and it feels pretty damn good! They've treated me like a hero. Their tech skills and their fanaticism are even stronger than I'd heard. They celebrate that damned arm like it was the second coming of their Great Prophet Jerodyn!
I figured bringing them that alien arm would land me in senior management. Well, they made me a senior Combot commander, so now I'm higher ranked than Diego! Well, it's Diego's loss that he didn't come with me. Diego's blindly loyal to Rimtech, just like father was. If he's not careful, he'll end up another casualty of Rimtech's short-sightedness too.
Y: 64 / D: 363
The Theocracy seemed miffed about my last mission. It's a minor misunderstanding. Meanwhile, I've settled in at Neuropa. My staff are great. They're smart, loyal, and capable as any at Rimtech, but there's no real sense of "belonging" yet. They're all true believers, and I'm not.
Everyone knows Neuropa's religion is based on the aliens, but I had no idea how far that went. Neuropa revolves around the aliens and religious devotion to their memory and their artifacts. It's insane. Everything around here has some religious significance. I mean, look at this...even my personal log isn't just a log. I was told it was my place to record my personal confessions, and thus cleanse my mind for Hedoth enlightenment!
Oh well, lack of camaraderie is a small price to pay for how far I've advanced my career. Hah, I'd better be careful, or I might convince myself I miss Rimtech!
My next mission is to Hedoth II. Pretty basic stuff. Teach Mil-Agro a lesson. The Theocracy wants me to leave the enemy orbital forces alone, and, despite their holy-speak rationalization, it makes good tactical sense to leave survivors who can tell Mil-Agro we're no pushovers.
Y: 65 / D: 20
It's obvious that the Theocracy doesn't like my methods. It doesn't matter that I get results when none of their other Combot commanders can. Okay, so I'm not following their so-called "enlightened path". I think they'd be happier if I failed if I would just swear my infinite devotion to the Hedoth. But, because I won't, they've assigned some religious master to guide me. Well, I'll play along, but I'm not going to let him push me around. I didn't take it from Diego, and I sure as hell won't take it from this Komrov!
Y: 65 / D: 43
Wow, these folks have an amazing intelligence and espionage division. They know stuff about Rimtech that Rimtech itself doesn't know! When I asked if they knew if my brothers were amongst Rimtech's casualties, I was told that Stefan isn't with Rimtech...he's with Mil-Agro! What the hell is he thinking?! What possible benefit could there be with Mil-Agro?!
I asked Komrov why anyone would go to Mil-Agro. He gave me a silent stare, so I let it drop. He's not a bad guy, but he is weird.
Y: 65 / D: unknown
Currently being held prisoner by Rimtech.
Y: 65 / D: 56
My capture exposed me to a side of Rimtech I'd never seen before. The interrogations were brutal...what I'd expect from Mil-Agro, not Rimtech. If this is an indication of what Rimtech is becoming, I'm glad I left when I did! I can't believe I'm actually relieved to be back.
To hear Neuropa tell it, I'll even fight my family to defend Neuropa and its beliefs. Everyone around here keeps treating me like a hero. Gullible fools. It was Komrov who got us out of that prison and saved my life. First he escapes from the Mil-Agro prison during the Munich Uprising and now he escapes a Rimtech prison! He's the real hero, and he's getting none of the credit. I asked him if the lack of recognition bothers him, and he said he doesn't want any attention. He's such a gentle man, I don't understand why he's with Neuropa at all, let alone having been with them long enough to become a Magister.
Y: 65 / D: 57
I can't sleep nights. I keep thinking back to that screaming match I had with Diego in the prison. Diego actually blamed me for Stefan going over to Mil-Agro. He said I set the example by going over to Neuropa! I don't buy that, but I can't think of any other reason why Stefan would do such a thing.
Y: 65 / D: 59
My next mission is another one where I have to retake "holy ground" from Mil-Agro. The Theocracy frustrates me. Their only concerns are Hedoth sites and artifacts, and traitors to the faith. They ignore our enemies until they respass on a holy site. Wars aren't won that way.
If I ever get the chance to get back. I don't understand the High One. He doesn't even care about the enemy. All they want is alien knowledge to worship.
Y: 65 / D: 79
Rumor has it that the Theocracy has started some kind of Inquisition to uncover traitors in our midst. It's ridiculous and must be an excuse to purge the ranks of malcontents. There's no way any spy could infiltrate this bunch of fanatics.
Y: 65 / D: 83
Komrov is off on some secret project. Given his Magister position, I bet Komrov's part of the Inquisition. I've never been a believer, so I wonder how long it'll be before they come after me? Komrov warned me they'd use any excuse to kill me if it served their purposes. I just hope Komrov can shield me from them.
Y: 65 / D: 84
Is it my imagination or is everyone watching me? This is crazy. I've got to find a way out of this mess.
Y: 65 / D: 91
We're headed for Ice Sanctuary. It was one of the first Neuropan territories to be established before the war started. Now all three Corpos have been fighting for it for weeks. My job is to take it for Neuropa, once and for all, and give the Theocracy propaganda machine a big boost. Fortunately, Komrov is back to help me. He won't tell me where he's been or what he's been doing.
My plan is to win such a decisive victory at Ice Sanctuary that Neuropa will again tout me as a hero. That should clear me of any suspicion of being a spy. And this time I won't resist being their propaganda tool. I'll ask Komrov to recommend that I be shipped back to the Core Systems for recruiting purposes. Once there, I'll grab a berth on an Earth bound ship and find a new corporation. With my skills, I'll have corponations at my feet begging me to join them.
Sector 4 is the hot spot of the Corponation war. Everyone is fighting for it. If I can take it, maybe they'll stop suspecting us. (getting sick of Neuropa)
Y: 65 / D: 104
Komrov was the spy! How could I have missed this?! He didn't escape from Mil-Agro during the Munich 15040 Uprising, they let him go! I'll be it's no coincidence that Mil-Agro attacked the Rimtech prison we were in. They were protecting Komrov! He only brought me along to make it look less suspicious than if he alone had escaped!
I've been ordered to kill him, and why not? I don't care that he's betrayed Neuropa, but he used me. I want out, and if taking out Komrov will buy my freedom, so be it.
Y: 65 / D: 109
I've been a fool. They'll never let me go. Death is the only escape from Neuropa.
I thought I was using Neuropa, but they've been using me. I'm a puppet. They've manipulated me, all the while making me think I was using them. God, I may even be responsible for this whole war. What was I thinking, bringing that arm to Neuropa? I've betrayed everyone, and what has it gotten me? I've lost my brothers, my home at Rimtech, and I've killed my only friend.
It's too late for me to do anything about Komrov - I'll live with that guilt for the rest of my life - but perhaps one day I can make amends with my brothers for all the grief I've caused.
- Despite Jonus leaving Rimtech and joining Neuropa with the alien arm for the sole purpose to get rich, there is no evidence to suggest that he becomes monetarily wealthy.