Joselyn was Jason's twin and during his Robin years, after he'd left her behind, they had a very rocky relationship which mostly consisted of Joselyn trying to kill him. After his resurrection, they made up, and now that Jason was hanging around the manor sometimes, so would Joselyn if he let her in.

So, that's why, when you walked into one of the Manor's many parlors, you saw Joselyn sitting on the couch, halfway through a sandwich Alfred had made her.

Joselyn gave you a nod of acknowledgement. "'Sup?" She greeted.