Dion is a new character introduced in Metal Slug Attack.
Originally one of Abigail's spies, he was promoted to Lieutenant after she was impressed with his combat capabilities. He serves as her right-hand man and is a skilled fencer, using a rapier to attack enemies. He also carries a pistol for ranged combat. Much of his personal information is secret, as Abigail doesn't even know his actual name. In normal operations, Dion typically wears a standard army green uniform; in special operations, he changes into a red variant.
Alongside serving as Abigail's lieutenant, he also serves as her second-in-command for ACE. Unlike many of his fellow allies, Dion retreats if the battle becomes too dangerous for him.
First appearing in "Hot Trap", he captures Caroline and Towa who were busy testing new vehicles for the growing Ptolemaic rebellion. While the two mechanics resist and free more prisoners, he is able to recapture Caroline, and sends her to work as a prisoner to create machines for the Rebel Army.
During a meeting in the past, when the Professor failed to show up, Dion asked Abigail if he should forcefully bring him due to his constant absences. Abigail tells him not to, though she states that it would be nice if he could send someone in his place.
Dion later "allows" Caroline to escape with the Sky Jupiter Queen and causes a panic at the prison, angering Izabella who had started to take a liking to Caroline. Dion does not state why he allowed her to escape, though it is presumed that he was trying to find the Ptolemaic base.
When Geweih Metzelei invades Earth, Abigail decides to work with the Regular Army much to his concern as they are enemies. Abigail points out to him that they can learn about the Regular Army's latest developments. Geweih proves to be much stronger than expected, and Abigail has Beatriz's forces retreat, though he is unable to contact her himself. This prompts Abigail to go out to find her sister, with Dion accompanying her. Dion takes Vicky away while the two sisters have a personal moment, and consoles Vicky himself, though he becomes speechless when she asks him to bring her back to base before the United Shop closes.
Padwah later brings Caroline back to Rebel Army custody, alongside Towa, who Dion was unable to capture in their initial encounter. He sends the two off to a Regular Army base to bring combat data from Caroline's newest ShootingRay model. During the operation, he was contacted by the Ptolemaic Army, who sent bodyguards to protect Caroline. After the attack was repulsed, Dion was content with the data obtained and had the two mechanics returned to his custody. Unfortunately, they would later be freed by Yutong in another battle.
Despite the loss of the young mechanics, Dion began preparations for another mission, working through the night. On the day of the operation, Abigail asked him if he should take a rest, but he declined the order and instead completed the mission under a technicality. As they returned to base, he saw Abigail with a reindeer plush she had obtained from the Christmas Doloma. When she told him that it reminded her of a gift she gave to Beatriz, Dion told her that she should take some time off, stating that no one would dare deny her request as she was a major contributor. He then took his leave.
Dion later heads to an underwater facility where the Rebel Army captured a Invader, visiting alongside fellow ACE members Romy and Katalina. When they discover hostiles attempting to enter the facility, they all agree that they cannot let the Invader escape and that they will destroy the facility if need be. To Dion's surprise, he finds that the intruder is none other than Leone and asks what she's doing. Although he appears to sympathize with her, he battles the prisoner and her Invader as they are hostile towards them. As the facility begins to crumble, Leone saves her seniors from drowning.
Shortly after the incident, Dion learns from Olga that she and Destrade spotted a pink tank, the former wanting to use it for training. Suspecting that it would be related to Leone, he agrees to send a squad out for the tank and goes with her. They run into Leone and Halle. Dion vanishes and sneaks up behind Leone, although the former ACE candidate is able to sense him. He then asks Leone if she's still trying to get the Invaders off her tank, before following Olga into chasing the Invader. When Olga seemingly incapacitates the tank, Dion tells her to remain calm, but the hot-headed woman ignores him and gets tangled by the tank, only for it to be scared off by an arriving Leone and Halle. After they leave via the Rugname, Olga drags Dion with her back to base.
First appearing in "Subjugation Tactics", Abigail discreetly contacts him to begin her plan to kill the Professor. Beatriz, having heard rumors from Vicky that Dion might be trying to take Abigail's position, asks him what he is doing. He flatly states that he knows nothing and leaves to rendezvous with Abigail.
After taking out the initial sentries, Dion sets jamming devices per Abigail's orders to prevent the Martians from using telepathy. As Abigail carries out her part of the plan, Dion confronts Marty, who had set out to destroy them. Dion successfully stalls Marty long enough for Abigail to kill the Professor.
- He bears a certain resemblance to Raidou Kuzunoha the XIV from the Devil Summoner series.
- He is the third male character to wear sunglasses since Clark Still and Tarma Roving.
- Dion is the third Rebel Army character that doesn't die in battle, behind Abul Abbas and Emma; rather, someone contacts him on his earpiece and he then flees in a panic.
- Though his illustrations depict him as using his rapier with his right hand, in-game he wields it with his left hand.
- This was eventually fixed with his Imperturable variant illustration.