Filler Arc Rewrite.
As we all know, Season 1 of the World Trigger Anime has a Filler Arc (The Fugitive Arc) wedged right into the middle of the B-Rank War Arc running from Episodes 49 - 63. It's no secret that the fandom treats this arc with either indifference or derision due to the plot and characters. Season 2 onward pretty much renders this arc non-canon. I've been thinking this over for a while and I think a Filler Arc could have worked if done differently. I've come up with a little idea for a Filler Arc.
In Shizuka City, instead of encountering Xeno and Lilith, T2 encounters a world-renowned robotics scientist Dr. Dimitri Landers who turns out to be a Neighbor. T2 meets Dr Landers after failing to destroy a weird Trion Soldier that was attacking a civilian, draining them of their Trion. After introductions, Dr Landers asks for T2's help in hunting down the Trion Soldier seeing their abilities with Triggers. He would have gone directly to Border but feared for his safety given Border's general hostility to Neighbors (Landers didn't know Tamakoma Branch existed until meeting T2). T2 says they'll think it over and Landers gives them his phone number to contact him.
After some deliberation, T2 agrees to work with Dr Landers but they also give Border HQ a heads-up. During the arc, we get Dr Landers' backstory where he's a Neighbour whose real name is Demetrios. He comes from a Neighbor Nation where he was a Scientist specializing in Trion Soldiers. His nation's World Trigger was irreparably damaged and while everyone was in denial about their coming doom, Landers could see the writing on the wall and got the hell out of there before the nation eventually died.
He landed on Earth around 30 years ago and found the world fascinating. Eventually crafting an identity for himself, he learned to combine Earth and Trigger Technology to become an authority in Biomechanical and Robotics Engineering. The Trion Soldier they are chasing in this arc was his latest creation, a robot designed to cleanse soil or harmful materials and pollutants, making it suitable for agriculture. But now, something has taken over the Trion Soldier and is making it attack people. Of course, Border sends other agents to assist in the hunt of this Trion Soldier but also keep an eye on Dr. Landers now that his true identity as a Neighbour has been revealed.
Eventually, it's revealed that the reason the Robot has been attacking people is that it was reprogrammed by Dr. Landers' long-time research partner, Dr. Yusuke Aoba, a scientist who also specializes in Robotics, but has a military background. During their time working together, Dr. Landers shared his true backstory with Dr. Aoba, including what the Neighbourhood is like. Aoba being an ambitious (and power-hungry) person thought Dr. Landers was wasting his talents because Trion Soldiers could effectively take over the world. Thus Aoba was working in secret behind his partner's back, quietly working on his own research to his own selfish ends.
Aoba has created his own small legion of Trion Soldiers which he unleashes on Shizuka City, using the Trion he siphoned from his victims. Cue the big final battle where all of Border's Official Agents go to Shizuka City to fight. Aoba is defeated and not wanting to be taken into Border custody, uses a device to open a Gate to escape to whatever random Neighbour Nation is close by. The arc would wrap up with Dr. Landers thanking T2 and by extension Border for their assistance. When asked if he'd join Border, Dr. Landers declines the offer, saying he prefers working on his own terms and feels Border would restrict his research.
I think this idea would ask some interesting moral and ethical questions regarding Neighbours. The majority of the Humanoid Neighbours we've seen so far in the series have been varying levels of hostility. However, here we have a Neighbour who has been on Earth for 3 decades yet has assimilated into Earth Culture and is even helping improve the world using Trigger Technology. It would make you ask whether it's right to persecute Dr Landers based solely on the fact that he's a Neighbour. I can see some Shinoda-Faction members thinking that way and a counterargument being the fact if Dr. Landers wanted to do something bad to Earth, he would have done so by now. There's also the paradigm shift of a human from Earth being the true antagonist of this arc, misusing Trigger Technology for their own selfish ends.
And that's just about it. The main idea I had when thinking this up was "**Not all Neighbours are Assholes, but not all Assholes are Neighbours**" in that being a Neighbour doesn't automatically mean you're a threat to Earth/Meeden and conversely, just because you're from Earth, doesn't mean you can't be a threat if given access to Trigger Technology. I'm not sure how well this would fit into World Trigger's world and canon but I don't think it would be too far-fetched. Let me know what you think.