Exos that havent been rebooted yet are supposed to have their human memories [spoiler]but Clovis-1 didn't know anything but the bare minimum of being a human being[/spoiler].
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The lord explains that the exos fought the vex before the collapse in an isolated war on Europa after he opened a man made vex gate. By the end of the war the Clovis exo became haunted by his past so he wanted to forget it all and he had his memories erased with the strangers help.