Who is Marcus Parker and Anna Stefanovitch from The Midnight Club and what is their importance?

Marcus Parker is Isiah's younger brother. He is a promising boxer, who mistakenly gets involved with the mob. When he refuses to play by the mob's rules, he is transported to a motel where his captors force feed him drugs over a long period of time. In the end, Marcus is given a fatal overdose. Isiah is devastated by his brother's death, and he believes St.-Germain is responsible.

Anna Stefanovitch is Stef's wife. She is the love of Stef's life. When St.-Germain realizes that Stef is getting too close, not only does he shoot Stef in the back, putting him in a wheelchair, but he also goes to his home and shoots Anna. Anna dies immediately. Devastated by the death of his wife, Stef finds himself unable to go on. Her death and revenging her death becomes the focus of his life. When Stef meets Sarah, however, he begins to put his anger behind him and learns to live again.