In a previous idea I mentioned Remus getting sent to an alternate reality, this is just expanding upon that.

Remus and Roman get in a fight where Roman says, "You will never know how hard it is to be me!"

And Remus responds with, "oh yeah well I bet it's super fuckin easy to be you!"

Then Remus wakes up in an alternate reality where he and Roman have switched places.
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Another idea I have for Remus, is that after Janus and Virgil are both gone, he's all alone. While alone he's walking in the dark mindscape when he sees another side. Congratulations it's the orange side and Remus is going to befriend them.