Dos Santos is a giant, sturdily-built man with rock-like features and a moss-like stubble. He is compared to looking like a steel statue. He has dark, sunken eyes, faintly-connected eyebrows, and a sharp jaw. Santos's hair is dark, frizzy, and puffy, with a slightly receding hairline.
Dos Santos is a stern man who loyally follows Alhorn, even after his boss murders his entire family. Although he had cut ties with his family prior, he still feels confusion, resentment, grief, and guilt upon seeing their corpses. He acts cautiously around Alhorn, careful not to upset him. Santos is also quiet unless he has a good reason to speak.
His eyes have a penetrating glare when his sight is set on someone, and he is calm enough to be compared to a towering ice shelf looking down at his enemies even when their gang's fortress is set on fire by Octavio.
As if brainwashed by Alhorn, Santos is very interested in seeing the abilities awakened by Sasha Loggins and the other prisoners. He believes that he did them a favor by capturing them since they could be rulers of the new world Alhorn wants to create by using their new powers. Although he kills people, his expression lacks sadism, and he instead acts like a detached factory worker looking only to complete his mission. By entangling Sasha and the prisoners in his forest, he thinks he is preparing them for fighting in wars.
- Main article: La Casa Verde
La Casa Verde can grow underground rhizomes at an abnormal rate, allowing Dos Santos to control all of the roots, plants, and trees that they are connected to. He can essentially grow an entire forest in a matter of seconds and manipulate the plants of the forest to move as he pleases.
Dos Santos was born in Santa Rosa District in Lima, Peru. He lived in a middle class residential area and had happy memories he shared with his parents and older sister, but was later completely estranged from them for unknown reasons. At some point, he joined Fernando Alhorn's gang and became his closest aide, also awakening his Stand. Both Alhorn and Dos Santos are included in the personas más peligrosas list.
In 1974, he fought Sasha Loggins and Gustave Shaulo Messina after they infiltrated the gang's base. He captured them and tied them up using his Stand, placing them in a quarantine ward in Alhorn's citadel.
Dos Santos heads to his family home to pick up Alhorn, who was visiting there. However, he sees the corpses of his parents in the living room when he arrives. While feeling troubled, he goes to the bedroom and tells Alhorn that he should return home soon. However, Alhorn tells Santos to relax and have some drinks. Consequently, they end up staying in the house for three more days while drinking. Santos asks his boss to put his clothes on since it's not his house. Instead, Alhorn then asks Santos what the essence of war and murder is, before explaining that they are asymmetrical because they never have equal actions and results. Santos tells Alhorn that there are people waiting for him in their cells, so he finally decides that they should leave and tells Santos to grab the Bow and Arrow. Santos had been avoiding looking to the left of the bed the whole time, where the dead bodies of his pregnant older sister and her husband were laying. He hesitantly pulls the Arrow out from his brother-in-law, trying to stop himself from shaking.
As they head to the living room, Santos laments the death of his family despite cutting ties with them years ago. Alhorn asks Santos what he expected when they decided they would come to his home. He decided to shoot them with the Arrow to see if they would awaken powers like Santos had. As they leave the house, they are immediately surrounded by Santa Rosa police officers, who points their guns and have armored cars behind them. Alhorn suspects that Santos set him up, but Santos denies the accusation. Alhorn then orders Santos to wipe out the police officers using his powers.
Battling the Intruders
Later, he confronts Sasha, Octavio Luna Kan, and Joaquín Ruiz-Jorruda when he finds that their base is on fire. He is surprised to see that Sasha survived from the Arrow. Dos Santos demands to see the power she gained from the Arrow, but she denies having any such ability. He summons his own ability, La Casa Verde, causing the surroundings to change dramatically into a forest. Dos Santos hovers above them, manipulating the forest as an extension of himself. Sasha and Octavio find themselves battling not just horizontally but also vertically, as the roots and trees expand in all directions. Dos Santos taunts Sasha, reminding her of her previous failure against him.
Santos persistently goes after Sasha, who tries to protect a young boy held captive in the roots. Santos nearly kills both of them by wrapping his roots around their necks, until Sasha awakens her powers. Small birds hatch out of Sasha's hat, making Santos momentarily pause his assault.
Octavio manages to place Dos Santos in a choke hold by clinging onto his back. While Santos tries pushing Octavio off him with his roots, Sasha uses her birds to give one end of her braided cord to Lisa Lisa, while another bird ties the cord around Octavio's arm. Sasha and Lisa Lisa then pour the Ripple into Sasha's braided cord. The Ripple passes through Octavio, using him as a medium, and reaches Dos Santos. His jaw lifts and his body bends backward, finally incapacitating him and ceasing the growth of the forest.
- “My aim here is only to place you all in a situation where you cannot fight back or defend yourselves. That is the kind of difficult guerra we are all headed for. Just like this bosque. There, your feelings of brotherhood or kinship will not matter. All you can do is fight – strangle your own fate and struggle up towards the sunlight.”