Will Snitches attack each other?

Solution 1:

The "deadly" trait (a prisoner can kill in one hit) only comes into play when a prisoner gets into a fight. It does not increase the chance of a prisoner getting into a fight. They will fit in nicely in your Protective Custody wing.

A more problematic combination of reputations is "Gangmember" and "Snitch", or "Volatile" and "Snitch". Gangmembers are known to start fights with other gangmembers. Volatile prisoners start fights without a real reason. Since their is rarely trouble in Protective Custody, and therefore usually less guards are needed there, this can have worse consequences.