In 1900 PD, Santos held the rank of Lieutenant Commander and served as chief engineer of the light cruiser HMS Fearless. She had served on the ship previously under Captain Rath; she and Alistair McKeon had known each other for some time and considered each other friends. Some time later, Santos discovered that the Havenite freighter Sirius was equipped with military-grade impellers. When the ship broke orbit and tried to flee from the system and summon Havenite "support", the Fearless engaged it and the First Battle of Basilisk began.