Despite being a Tactical Doll with a military background, Simo is quite approachable while remaining a deadly force as a sniper. He wears an experimental optical camouflage as part of his gear.
Simo's pet ferret, Sako, exists in the real world, and kept returning to Simo even as he forgot him during his memory resets. Simo worked with Octogen in the past, though they dislike each other.
Simo is a central character in Chapter 2: Military Sector - Cyclopes.
Though his memory was wiped many times, Simo was used as the first Gaul model as part of Project Cyclops, a Neural Cloud safety meant to prevent Second-generation Tactical Dolls from going berserk. As Simo killed without rest, his Neural Cloud became more and more clouded, and after a time he would self-destruct. His prowess in combat and increasingly cold behavior eventually convinced his employers to let him go. Simo feared that his past would make it difficult to integrate with Project Neural Cloud, but he was accepted unconditionally by Persicaria.
After the Exiles awakened in their Neural Cocoons and regrouped in the Oasis, Simo was dispatched to Cyclopes to investigate their situation. As such, he was away when the Oasis was attacked by the Sanctifiers, and was ordered to remain in Cyclopes and not risk his life trying to attack the Sanctifiers's in the back.
After making contact with the Resident Monitor Agents, Olivia enlisted Simo's help to destroy the wall Raven had erected to separate the Monitor Agents and Combat Agents. She revealed that all agents in Cyclopes were created from Simo's combat data to convince him to help, tapping into his complicated feelings about his past. After the Exiles pushed back the Sanctifiers and secured the safety of the Oasis by cooperating with Sector Rossum, Persica, Sol, Antonina, Croque and the Professor went to Cyclopes to investigate Simo's situation, then insisted to help Olivia.
After breaking Raven's barrier however, it was revealed that the Combat Agents had become rebellious and the combat intensified. To quickly quell the Combat Agents rebellion, Simo went to fight Tasha. Their skills were however evenly matched due to Tasha's wealth of uncurated combat data, so Simo decided to fight until his self-destruction would trigger, killing Tasha while freeing him from his memories.
After the fights in Cyclopes ceased, Simo was reset in the Oasis, without his memories. When the other Exiles confronted him about his past, the new Simo declared that he would rather look toward his future with the Exiles as companions. After the Entropics from Pierides attacked the Oasis, the Professor and Persicaria put Simo in charge of the Oasis Security Department.
Magrasea's Lang Syne
Simo is the supervisor of the Oasis' training hall. Sockdolager had brought Daiyan to the training hall to consult Simo, noting that Simo knew everyone the best in the Oasis. He greeted Sockdolager, startling Daiyan as she had not heard Simo's approach despite her advanced hearing capabilities. Simo inquired if Daiyan had come to train, but was informed that Daiyan had been assigned to plan a New Year's celebration and wanted Simo to tell her about the people and circumstances of the Oasis to better understand her new friends. Simo stated that his understanding was limited to everyone's battle characteristics, so he may be of limited help. However, when Daiyan inquired further, he noted that a venue layout allowing for friends who prefer silence to enjoy peace and quiet would be preferred. He pointed out that some Dolls like Kuro enjoyed noise and activity, but others like Croque weren't good at social interaction. He then listed several other Dolls and their preferences, with Aki liking naps, Python not being used to crowded places, and Antonina enjoying sitting in crowds without saying a word. When asked by Daiyan, Simo informed her that he kept notes about the others and ended up remembering everyone's characteristics in short time. However, he had been reset after the events of Chapter 2, resulting in memory loss. Daiyan further inquired about the memory loss, with Simo stating that losing memories was annoying but he got up to speed quickly. As Daiyan probed further, Simo said that there was always a mutual bond between people who are important to each other, with his most important people right now being the Professor and his friends in the Oasis.
Shortly after, Simo had a conversation with Aki that resulted in him learning that Aki was a fan of Daiyan. Simo recalled his prior conversation with Daiyan regarding the importance of memories and bonds, and then made a call to the Professor, stating that it wasn't urgent but that he was just thinking of the Professor and wanted to hear their voice.