One of the many surprises for this season - possibly the biggest, since unlike the return of Ray and Sara it wasn't spoilt by Legends of Tomorrow promos - was the reveal that John Diggle's brother, Andrew, wasn't actually dead. Believed to have been killed by H.I.V.E., it instead turns out that he is working for the organisation as one of their Ghosts. Team Arrow risked their lives to get him out of there, and now he's caged up to prevent him either running back to Damien Darhk or simply killing himself, because he's so brainwashed. John has got the body of his brother back, but he's a long way from actually getting the person back, and quite how he'll manage that isn't easy to see. Whatever happens is likely to influence John's actions for the remainder of the season, and resolving it in the mid-season finale would make things very interesting for his arc going forwards.