Also, since most things are biologically compatible in the Trek universe, a SGA Wraith scenario is plausible: something living on Remus could have turned the Remans into what they are in the 2370s, through infection or parasitic penetration. This could work a bit faster and more consistently than "mutation through radiation" or other such classics, and wouldn't even need to be hereditary. It could affect each newborn separately.
Outside the novels, it's still possible the Remans are unrelated to Vulcans and Romulans, and are instead an oppressed native or imported species. Taking the novels into account, it might be fun if the people on Romulus were fed government propaganda which claimed that Remus was an agricultural planet where people very similar to Romulans lived their happy lives. The horrible truth of a gulag for aliens and Romulan dissenters would be silenced to death...
Timo Saloniemi
Outside the novels, it's still possible the Remans are unrelated to Vulcans and Romulans, and are instead an oppressed native or imported species. Taking the novels into account, it might be fun if the people on Romulus were fed government propaganda which claimed that Remus was an agricultural planet where people very similar to Romulans lived their happy lives. The horrible truth of a gulag for aliens and Romulan dissenters would be silenced to death...

Timo Saloniemi