Fernando is fifty years old. He has a dismissal he never saw coming, and a question that will not let him sleep: who occupies his chair now? Thirty years as the best in the room end in a fifteen-minute meeting. What has replaced him is a machine. It has no face, it does not sleep, it does not age. And it did not come to compete with him: it came to replace him.
La sustituta (The Substitute) is told in two voices. That of Fernando — human, and at times broken — who narrates the worst year of his life and, at the same time, the most fertile. And that of the Algorithm — cold and without remorse — which explains why it has arrived to stay. The true battle is not Fernando against the machine. It is Fernando against the idea that thirty years of experience can fit into a prompt. And it is the machine, indifferent and powerful, discovering that there is something in the equation that never quite adds up: the human soul — contradictory, illogical, and impossible to replicate.
A book that reads like a novel, with the unease of someone stepping onto unfamiliar ground, and that ends by posing questions even more uncomfortable than who keeps the job: who, in the end, decides who we are and how we work?

Sixto Arias
Sixto Arias (Verín, Orense, 1968) is a serial entrepreneur and an expert in innovation, digital marketing, and artificial intelligence. He has been a founding partner of Result Venture, Movilisto (acquired by iTouch), Mobext (acquired by Havas Media), Capaball, Talent, and Incontratáveis.
He lives in Portugal, where he combines his work as a professor with investing in various startups. He has taught courses in digital marketing, innovation, and artificial intelligence at leading universities and business schools in Portugal, Spain, Colombia, and Finland. He is the author of several books and numerous specialized articles, and publishes regularly on his blog: sixtoa.substack.com.

Óscar F. Rodríguez
Óscar F. Rodríguez (Santurce, Vizcaya, 1978) has more than twenty-five years of experience in the digital advertising and media industry. Passionate about technological innovation, he currently combines his professional activity with the learning, dissemination, and practical application of artificial intelligence tools.

INDEX
Prologue ······ 9

The Geometry of Farewell (Fernando) ······ 13
To Hell with Us (The Algorithm) ······ 25
The Skin beneath the Uniform (Fernando) ······ 33
The Uncanny Valley (The Algorithm) ······ 47
The Inventory of the Intangible (Fernando) ······ 53
Trapped in Your Own Nature (The Algorithm) ······ 63
Production Budget (Fernando) ······ 67
Immortality (The Algorithm) ······ 71
The Truce of the Small Hours (Fernando) ······ 77
You Have Given Us Everything (The Algorithm) ······ 81
Wrestling with the Damn AI (Fernando) ······ 87
The Ethics of Coexistence (The Algorithm) ······ 95
If You Can't Beat Your Enemy, Learn from Him (Fernando) ······ 101
We Are a Deflationary Force (The Algorithm) ······ 109
The Carpentry Workshop (Fernando) ······ 115
Who Are We, Really? (The Algorithm) ······ 123
Don't Stop Moving, but Don't Run (Fernando) ······ 127
We Need Your Body (The Algorithm) ······ 133
Flesh as a Peripheral (Fernando) ······ 139
An Unlived Life (The Algorithm) ······ 153
The Shop Window and the Hunters (Fernando) ······ 157
Good Old Claude (The Algorithm) ······ 167
Casting of Shadows (Fernando) ······ 179
AI Is Democratization (The Algorithm) ······ 189
Turning Off the Prompt (Fernando) ······ 195
We Are Going to Vampirize You (The Algorithm) ······ 203
The Art of Deciding and the Science of Signing (Fernando) ······ 209
Learn (The Algorithm) ······ 215
The Fatal Leap (Fernando) ······ 221
Acknowledgments ······ 227