Yvan-A113

Yvan-A113, born Yvan Dmitrievich Guillou, is a Spartan Operations Headhunter, formerly working as a Headhunter within of the SPARTAN-III program. Yvan was born on the world of Biko on October 19, 2525 to Kate Guillou and Dmitri Zaytsev. The couple was an odd pairing, with the latter being a high ranking on Biko and the former being a young  agent who had been spending the past five years infiltrating and monitoring his cell for the UNSC. While there was a brief period where the pair truly did seem to love each other, with Kate faltering in her mission, this didn't last and, in early 2526, during the, Kate killed Dmitri and completed her mission, leaving Yvan with only one parent. However, this, too, quickly changed, with Kate deciding to hand over the infant Yvan to ONI, desiring to dedicate her time to her job rather than the child she had with the man she killed.

Once handed over to ONI custody, Yvan was quickly identified as being a potential candidate for 's planned s. As such, he spent the next few years undergoing extensive genetic therapy to prepare him biologically for the challenges he'd be expected to face. Additionally, he found much of his childhood to be quite regimented and militaristic. While there wasn't any true physical training during this time, once he reached about three years old, his life was strictly scheduled out for him with only minimal time to spend interacting with the other kids around him; enough to learn how to socialize but not so much that he'd grow too individualistic.

While he never ended up becoming a due to the decreasing funds and departure of Dr. Halsey removing the second class from the picture for the near future, the arrival of Alpha Company in late- presented ONI with an opportunity to make Yvan a  instead, receiving the designation Yvan-A113. The extensive preparatory training and genetic engineering that had seen him become one of the first candidates selected for the new program also saw him reaching well beyond expectations during his training. Particularly working well with field and stealth exercises and exhibiting a cunning mind for wilderness survival, Yvan was chosen to be removed from the main company to be trained as a headhunter.

His training saw him on a team with fellow headhunter candidate Ford-A272 with the two eventually becoming partners for their future deployments. While, as headhunters, they avoided the catastrophic that saw the deaths of the 300 Alpha Company Spartans deployed to, their high-risk missions saw them facing their own struggles through the years, facing brushes with death several times over the war. Eventually, these brushes caught up with the pair when, during the final years of the war, Ford was killed in action, leaving Yvan to fill in for spots on other headhunter teams until the program was reintegrated into Spartan Operations and the idea of lone operators was introduced.

While he remained qualified as a Headhunter, the changes made to the program following its absorption into Spartan Operations left Yvan deploying on standard missions as a rotating asset between teams from the  for much of the post-war era. However, due to his qualification, he often also saw deployment for highly classified missions as well. While the first few of these saw him deployed as part of two-man "BINARY" teams, it quickly became apparent that he didn't work well with his new partners as he had ever worked with Ford, leading him to typically see action as part of the one-man "LONEWOLF" team structure, where he excelled. This method of rotating deployment remained the norm for Yvan through the post-war era leading up to the.