Marcus Seria was a large Irish man who adopted Conner and Abigail as his own, coming to the surface with them after he became a Tortoise Big Daddy.
Marcus Seria was born in 1935 in New York City, his family was very loving and caring and helped him with all of his goals in life, resulting in Marcus becoming a champion boxer. After receiving an invitation to Rapture from Andrew Ryan in 1952, Marcus found a Bathesphere and went down to Rapture for the first time, being introduced to The Fighting McDonagh's Tavern and The Seahorse, in which he found Abigail and took her in as his own. After taking care of Abigail for a few years, Abigail was kidnapped while they were asleep when Abigail was only five years old. Once Marcus found out about her kidnapping, he went around Rapture putting up flyers and asking people if they saw her, even going so far as to ask Andrew Ryan himself. One day, however, Marcus saw Abigail walking with Deca, one of the few female Alpha Series. Enraged, Marcus ran up to the Deca and yelled at her to give his daugter back, with Deca actually handing Abigail to him without any resistance. Astonished, Marcus thanked Deca, and said if she wished, she could live with him in his soon to be safehouse. A few months later, Marcus saw a Little Sister being harassed by a male Toasty Splicer, seeing her protector, a Bouncer, dead by a pile of used Oil Canisters. Grabbing the Splicer from behind, Marcus socked the the Toasty across the face so hard he fell straight to the floor, and after punching him a few more times, caused the Splicer to run away in fear. Once the Splicer was far enough away, Marcus held his hand out to the little girl, picking her up and walking her back to his home, starting his business into becoming a savior for all Little Sisters.
Charge: Marcus charges at an enemy, dealing major damage and knockback.
Shoot: Marcus shoots his shoulder-mounted Rocket Launcher at an enemy, dealing incredible damage with large knockback.
Rocket Launcher Slam: Marcus slams his rocket launcher into the floor, causing a large earthquake, knocking foes off balance and stunning them.
Rollout: Marcus rolls into a ball-like form and runs over enemies, causing them to fall over and take continuos damage. (Does not knock over Protectors but still runs into them and knocks them off balance.)
Thunder Clap: Marcus claps his hands together with incredible force, causing all enemies to be thrown across the room with great force, resulting in an instant kill to low-level enemies.
Fist Slam: Marcus grabs an enemy and punches them into the floor, causing medium damage and foes to be stunned.
Dynamite Punch: Marcus runs right up to an enemy and suddenly punches them across the room, resulting in an instant death to lower-level enemies. (Merely knocks Protectors back)
Heart Breaker: Marcus punches his arm right through an enemy and rips out their heart, crushing it in his palm. (Still affects Protectors but only takes a third of their health away.)
Spine Ripper: Marcus rips out a foe's spine, resulting in an instant death for mose low-level enemies. (Only takes a fourth of a Protector's health.)
Skull Squisher: Marcus grabs an enemmy's head with his hand and crushes their skull in his hand, throwing the lifeless carcass across the room at another enemy nearby. (Eliminates a sixth of a Protector's health and causes them to be stunned from their crushes helmet for a short time.)
Chest Cracker: Marcus rams his elbow into an enemy's ribs and destroys their whole chest, resulting in an instant death. (Takes a third of a Protectors health away.)
Stomach Wrecker: Marcus knees an enemy in the stomach, destroying their whole midsection and killing them instantly. (Takes a fifth of a Protector's health away.)
Neck Snap: Marcus sneaks up behind an enemy and snaps their neck, killing them.
Thurough Examination: Marcus rams his fist right through a foe, ripping out their innards before kicking them to the floor.
Assasin's Glory: Marcus grabs a foe from behind and slashes their neck with his Wrist-Mounted Blades.