Before I start this thread, I’m gonna say something just so we’re clear:
Roman is by far my favorite character, that being said, I might “romanticize” his actions or something like that, so I apologize if I do so.

Trigger warnings for the thread: Betrayal, lying, being left out, etc. (If I need to add more I’ll add them in each tweet)

I’ll be theorizing a bit, this might be very long thread, but ill try to explain the relationship between Roman and Janus from “Can lying be good?” to “Putting others first” to try to understand Roman’s actions in POF.

Let’s start with Janus’s first appearance. When he revealed himself, Roman was the first one to acknowledge he was “very kind”, and Janus responded with a compliment, “I love the new outfit, Roman” and Roman responded with a very sincere “thank you”

Even though Janus was clearly lying, Roman seemed to enjoy being complimented and didn’t realize how false the compliment was.
My theory is that, at first, Roman thought Janus was kind because of the compliments, he trusted they were real, and because of that, he trusted Janus.

Maybe this is because of how insecure Roman really is. And Janus was the only person who constantly complimented him.
Roman takes the compliments very seriously, enough to consider Janus “kind”

In SVS, we see Roman supporting Janus, being friendly with him and clearly being on his side. Joking around and things like that.
Janus still compliments Roman as usual, even saying “You know I love you”

But something changes in POF
Roman refuses to accept Janus’s compliments.

He refuses to listen to what he has to say, and repeatedly calls him evil.

But this is the line that made everything “click”

He’s clearly talking from self experience.
Between SVS and POF, Roman realized that Janus was lying to him all along

He was hurt, and didn’t believe everything he said anymore.
The only person that constantly complimented him was lying to him.
He now understood how cruel Janus could be, and didn’t wanted him to be accepted for this exact reason

Roman was very emotional in POF, and started telling everyone that they shouldn’t accept accept him, and that they would be in danger if they did.

He was ignored, and Janus was accepted either way.

And then, the name reveal.

This is very important, Roman didn’t want anything to do with Janus, and when he revealed his name, he couldn’t care less, to the point he made a joke about Janus’s name

But Janus backfired very cruelly.
He knew Roman and knew that he was very insecure, so he hit were it hurt.
He called Roman evil. He compared him to Remus, and may I remind you what Roman thinks about Remus.

Remus is everything Roman doesn’t want to be, and Janus knew that.