It will be a long post, bare with me.
Let’s be completely honest: Providence also a terrible person.
Idk what’s up with worms, if it’s an allegory or not, but either way my point stands. Mitrix technically a deviant child, he haven’t seen his deeds as something bad, “he was just curious”. And Providence never addressed his feelings until much much later Mitrix finally figured it out. And it’s not the first instance, but just a beginning of huge miscommunication.
Mitrix taught Providence to create and always considered his preference (“…don’t you love soul?” (Bulwark’s Ambry log), “yes, trees are beautiful. I agree. We will have many trees” (Sundered Grove log)). When he sealed away Aurie he also considered her. The fact that cage is a cage still very depressing but it shows he wants him and Prov to be safe but also respect Prov creature at the same time. When She was away, Mitrix tried cheer Providence up by creating their statues as a gift, the ones we see in Prime Meridian (Prime Meridian log respectively).
The point is, he always tried to communicate with Providence. And since he constantly says in his logs like “say something”, “answer me”, it implies Providence did not communicate back. Mitrix has a point about creating less dangerous creature and about not infesting planet with random animals (excluding real life consequences there’s mentioned consequences in Tar log)(also same log: “My attempts to understand you have failed time and time again […] Is this my punishment?”). Did he phrase it badly? Yes. But they could just… like… talk!! Mitrix just sees world like that, and neither Her or Providence never spoke about it it seems. They basically just made it worse by completely ignoring the problem and Providence just kept being silent about his grudge against Mitrix (which is insanely shitty behavior).
Mitrix always cared about his brother and always understood he’s upset he just didn’t know WHY. From his point of view he just tries to keep them and their home safe. But he never ignored Providence bad mood and wanted to see him happy again (“I want to see joy on your face”, (A Moment, Fractured)).
Mitrix also was aware Providence is afraid of humans and suggested to communicate with them himself (“I know the planet you trail — of water and dirt. You fear their stability. That they will consume themselves. Maybe I will go there first”, (Commencement log)) Would it lead to disaster? Probably yes, but I see this as some consideration of Providence fears despite of Mitrix disgust towards “vermins” and whatever Providence doing abusing gates Mitrix created. It may be overthinking tho.
Mitrix even noticed that they drift apart and was very concerned about it (“Do you not see the gulf beginning to take shape between us? Do you not feel it? I do” (Bulwark’s Ambry Aphelian log)).
Moment of betrayal was just final snap after all years of this constant one sided conversation. It’s very radical in my opinion. Just complete stab in the back. Still Mitrix kinda tried to communicate the situation (Egocentrism log). And after that he completely lost it.
For me Mitrix seems like a deviant child that was misguided or even completely abandoned during his adolescence. It feels like She also preferred Providence more. Adding complete miscommunication with brother, who he definitely cared about, and we get a disastrous combination. But it could be different.
He’s not a pure evil. He’s capable of caring, considering his brother’s feelings and tolerating his behavior (he didn’t so anything against animals Providence was bringing on Petrichor!). He’s a good bio and tech engineer and was very glad to share his knowledge with brother. He very appreciated the time they spent together (“Have you forgotten what it was like to create something together? Do you not miss it?” Bulwark’s Ambry Aphelian log) and he really tried to make Providence happy again.
P.S after all should I mention that Mitrix was right?