Convicts can sometimes pacify the Rat King by chatting to him, similar to how they can tame rats by chatting.

Convicts can uniquely get their god to unpunish them as a special prayer boon (or maybe sacrifice gift that replaces an artifact). This requires some prerequisite like a certain amount of alignment record, so that it can’t randomly happen only a few hundred turns into the game.

Convicts get an alignment bonus by writing graffiti. (Graffiti has to come from a magic marker, or a felt marker in variants that have it.)

Striped shirts have random per-shirt prisoner numbers on them when you read them.