Blake's 7: ‘Mission to Destiny’.
CALLY: My people have a saying, a man who trusts can never be betrayed, only mistaken.
AVON: Life expectancy must be fairly short among your people.
Blake’s 7: ‘Rescue’.
AVON: He who trusts can never be betrayed, only mistaken. Cally once told me that was a saying amongst her people.
DORIAN: Cally?
AVON: Cally was murdered. So were most of her people.
I have no doubt this axiom was devised by series script editor Chris Boucher, as it is a complex musing on the personal code expressed is his all-time favourite Western, The Wild Bunch.
During a confrontation the outlaw Pike Bishop tells his gang:
"We're not gonna get rid of anybody! We're gonna stick together, just like it used to be! When you side with a man, you stay with him! And if you can't do that, you're like some animal, you're finished! We're finished! All of us!”
Later, we have this exchange:
BISHOP: What would you do in his place? He gave his word.
DUTCH: He gave his word to a railroad.
BISHOP: It's his word.
DUTCH: That ain't what counts! It's who you give it to!
This has two contradictory meanings:
1/ If you give your word you should stick by it.
2/ You can break your word if you feel you have given it to the wrong person/entity.
Obviously this moral code is highly subjective, and is held by a criminal gang who are being hunted down by an organisation which has the full backing of the law.
The saying of Cally's people also has two ambiguous and contradictory readings:
1/ If you trust someone and they turn out to be a false friend, the error lies with you for putting your belief in a deceitful person.
2/ If you trust someone, but think they have betrayed you, then the error is again yours.
‘In Children of Auron’ Cally's people were wrong to put their faith in Servalan, and were destroyed as a consequence.
However, during ‘Blake’, Avon was wrong to doubt his erstwhile leader, and this resulted in a cataclysm.