Jimenez is frank and talks without holding back. He is not afraid to assert his opinion on matters, often pessimistic, and does so numerous times to the chagrin of Zelenin who he is always at odds with whether it be on the topic of Zelenin's extreme zealousness or his persistent belief that humans should get along with demons. Jimenez likes to crack a lot of harsh jokes whenever he can and doesn't have any form of reserve about doing so, even having the gall to talk back at the Joint Project members and constantly throw verbal jabs at Arthur for his objective attitude. He is also quite selfish, acting on his own many times throughout the story.
He doesn't like to get close to people claiming that at times, one must be able to abandon an ally. In fact, Jimenez is suspicious of Mastema the moment they meet. With this belief, coupled with his personality and the circumstance of his survival, instantly makes him the black sheep of the Red Sprite. Ironically, he seems to get along with Bugaboo and the protagonist just fine, fostering close relationships between the aforementioned where he depends on them unlike any other people he's met.
When he becomes Awake, all the wild qualities about him amplify and he loses his humanity. Before, he wanted to desperately leave the Schwarzwelt but as an Awake demon, he no longer has such an intention and actually enjoys being there.
Although once a soldier in the military, Jimenez joins the Strike Team as a private contractor, despite military experience as a warrant officer. When the Blue Jet crashes in Sector Antlia, he is rescued by the protagonist and the crew of the Red Sprite, and he ends up joining the crew and receiving the Demon Summoning Program, which he is more than eager to use. He does not care about their mission in the Schwarzwelt, he only wants to get out of there. During the assault on Mitra's Tower on Sector Bootes, he rescued a Bugaboo from another demon's experiment, in return it volunteers to become his ally; he forms a close bond with the demon. While investigating Sector Carina, he was enraged at Horkos' absorption of Bugaboo, caused by his own recklessness and fury. He also met Mastema there, but did not get along easily with him. He was one of the crew affected by the Delphinus Parasite in Sector Delphinus, and was one of the two official ambassadors of the Red Sprite's crew sent to parley with Jack's Squad in Sector Carina.
During Sector Fornax's investigation, he is selected by Arthur to join the Jack's Squad HQ ambassadorial group, as one of the two officers who made contact with the Squad in Carina. Receiving a hostile reception, Jimenez insisted on remaining as a spy; Bugaboo escaped from him and wandered into the labs, finding the horrific experimentation within. Jimenez found him, and appalled at the horrors of the Squad's intentions, he destroyed most of the research equipment and released most demons. He was captured, tortured with a magnetic weapon, and used in a monstrously flawed Demon Fusion technique, which he only escaped from by fusing with Bugaboo, creating Awake Jimenez.
He confronts Jack by ripping open the Lightning and fighting off his demons as the Protagonist engaged Jack in personal combat. After Jack's defeat and disarmament, Jimenez will brutally kill Jack and immediately threaten to do the same to Ryan, Jack's second-in-command. However, he is interrupted by Zelenin, who sends him to be examined. After Ryan's coup and Zelenin's empowerment as an angel, Jimenez collects the captive demons abused by the squad and leads them to Sector Grus, saying goodbye to the Protagonist and giving him a rare forma as a token of the friendship they had.
He represents the Chaos alignment. If the protagonist chooses the Chaos Route, Jimenez remains in his Awake form, and is not battled as the protagonist instead chooses to join him in his crusade to have the Schwarzwelt expand and swallow the Earth to recreate the World of the Old Gods. In Neutral Path, he is battled in Sector Horologium as Awake Jimenez. In Law Path, Soil Jimenez, his final form, will be fought instead.
In the New Chaos Route, he is confronted by Alex, who reveals the truth of where she came from and what the future he creates in the original Chaos Route will bring. When the protagonist agrees with Alex's explanation, Jimenez realizes that he broke his own rule of survival of the fittest when he saved Bugaboo's life, the life of someone weaker than him. As Jimenez accepts that the compassion he showed there was a strength and not a weakness like he originally thought, while also vowing to create a world of possibilites with freedom, a new future is created and Alex disappears due to the alteration and having accomplished her mission before giving Jimenez her ring; which he would in turn give to the protagonist at the end of the new route.