Syd

Syd is the main protagonist of Quantum Theory. He is voiced by Keith Ferguson. His past self is unlocked as a multiplayer character by obtaining the trophy "Trusty Sidearm".

Role in Game
A former soldier who survived numerous battles, Syd has been traveling across the world looking for Towers to destroy in the name of revenge. After losing his most recent partner Nyx, he heads to a nearby colony upon learning that another Tower had sprouted there. Though Syd ends up helping the local militia breach past the building's defenses, only he survives the ordeal.

Upon encountering Filena, the two of them briefly clash when Syd attempts to break one of the lumenosynthetic reactors within the Tower. Both agree to hold a tentative partnership after finding a common enemy in the invading Diablosis. For his part, Syd is suspicious of Filena's backstory, having deduced that she's as linked to the Tower as Nyx was. As time progresses, however, he gradually bonds with her as they traverse through the upper levels.

Destroying another lumenosynthetic reactor has Syd recollect his past as an exile soldier for the Gillskins. Having seen so many deaths caused by the Arks, he becomes even more concerned for Filena's safety. Upon saving her from the mutated Thanatos, they confront the Seed in charge of the Tower and dismantle it, causing the whole structure to collapse. The story concludes with the two partners heading to another Tower to destroy.

Quotes

 * "All mine..."
 * "Mmm... Ammo..."
 * "Bye bye."
 * "Next victim."
 * "More, more!"
 * "One left... But not for long."
 * "This is bad..."

Gameplay
Serving as the player's avatar throughout the game's story, Syd can wield a variety of weapons with ease and perform different melee combos with his partner by tapping L2. On his own, he is only capable of performing a single punch as his melee attack. But with Filena, his attack options expand even more.