They share a Mom, though she would rather pretend that Mark here doesn't exist. He has been nothing but a let down, suffering from an eating disorder and severe depression his entire life, she's gotten tired of trying to pick up the pieces. Though Mark feels like she never tried in the first place. He is a bit jealous of his younger brother who appears to be perfect from outside perspective, though we can be sure kid brother has his own secrets/problems. They get along but with the age gap and growing up in entirely different states, they aren't exactly close. Would be up to you why/how he landed in Charleston and if they wind up being more friendly. In Mark's bio, I have his name listed as Noah Hargraves but that's absolutely up for change.