Since I shared Marina, he's her ex-husband, Martti.
Martti is Marina's sire and responsible for Marina ending up in her situation. The two met when they were young and had a family with two kids, Oliver and Saana. This was however was all ripped away one night where according to Marina she was attacked by her husband who appeared to be frenzied and Embraced her. She woke up and realized she was not normal anymore and ultimately gave her children up to her brother to raise.
Martti, from what Marina says has been on and off watching her from a distance but never have interacted with her since that night...until recently.
He did "something" to his great grand daughter to cause her to experience a First Change when her father confirmed to Marina she was never meant to be a Garou/Werewolf. Safe to say Marina tried to stop him and he staked her and said "I'm sorry." to her. She is very pissed off and has been aiding her grandson Julius to hunt her husband down. Whether or not she has the guts to destroy him is another thing, she has very complicated emotions towards him. ; ;
On top of all this? He is also an abomination and he is working with Pentex.