Ooh, Arrow fanfic tropes get surprisingly specific once you're deep in the serialized stuff. A big one is 'League of Assassins Reunion Tour', where Oliver's time in the League becomes this endless source of drama—old "brothers" showing up to drag him back, Nyssa al Ghul needing a favor, or some ancient LoA oath coming due. It's basically a narrative cheat code for pulling Oliver away from his Starling City life and forcing him into morally grey areas, which writers love.
Then there's the 'Tech Support Crisis', which is just a fancy way of saying Felicity gets kidnapped, her tech fails, or she's emotionally compromised so the team has to operate blind. It's a tension builder, but honestly, sometimes it feels like Felicity exists just to be put in peril so Oliver can have a 'save the one I love' moment. Makes you wonder about the agency of the character outside the damsel role.
Serialized fics also lean hard into 'Five Years in Hell Retcons'. They'll take a throwaway line from the show about Hong Kong or Russia and spin it into a 20-chapter flashback arc, introducing Original Characters as 'lost teammates' or 'unseen mentors' who shaped Oliver. It's a way to graft new mythology onto the canon, though it risks making Oliver's past feel absurdly overcrowded with secret tragedies.
Less common but fascinating is the 'Vigilante Network' trope, where Oliver starts formally training a rotating roster of protégés beyond just Roy or Thea—like, turning the Foundry into a night school for vigilantes. It scratches that found-family itch, but can drift into wish-fulfillment if every new character becomes instantly competent.