"I am always ready to execute.
"Unit: Three-CH-Zero, deploying."
Echo was not rescued by Cassidy. She was not in stasis for long enough for the Deadlock Gang to actually find her so that she would need rescuing. The "Echo Project" had been tracked the very moment the first file was "securely saved", so that if the progress made was not considered satisfactory... The unit could be liberated.
When Overwatch fell, those that had watched over the Echo Project decided that the unit going into stasis would be wasted. And that they did not feel the application of an autonomous and hyper-intelligent machine was appropriate; just... Letting her go free, to learn, to exist?
No. Better that she was appropriately contained, trained, programmed, what-have-you. And so, long before anyone could have found out from a friend who knows a guy who knew an engineer who knew a guy...
Echo was abducted. Remodelled. Reprogrammed. Reclassified.
The 3 'R's gave her new owners an idea. Maliciously, they kept her name... Almost the same. Now, she is the 3-CH0.
3, for the Rs. C, for Covert. H, for Hunter. And 0? So confident were they in their changes that they boldly stated that the '0' implied a zero survival chance.












