Arrow's second season picks up with Diggle and Felicity traveling to Lian Yu, where Oliver went after Tommy's death. Meanwhile, Queen Consolidated is left open to hostile takeover, and Starling City is plagued by copycat Hoods—earthquake survivors taking justice into their own hands.
I'm not sure why Ollie felt the need to go back to the island where he was stranded to come to terms with Tommy's death, but I like that his death made Ollie reconsider his mission and methods. The great fun of an origin story is the opportunity to show/see a character in development. The writers and Stephen Amell pull off a character who doesn't always know what he's doing, who plausibly can't foresee the ramifications of any one action he takes. Along with viewers, he finds out as he goes.