ok so I may have a canarrow au where sara comes back in season 1 while laurel/tommy are still together. She reconciles w Laurel (but doesn't tell her about the league) and stays w her so when it's tommy's bday party and Oliver shows up alone (b/c mckenna got called on the job idk) he has the shock of his life. and it's awkward but also they are both so relieved the other is alive. And then all hell breaks loose b/c sara is actually here on a mission to hunt down merlyn (i.e. her s3 mission)
and merlyn's minions are actually after oliver but Sara just steps in front of him and starts speaking fluent Arabic??? and then she pretty much turns into a ninja. Oliver joins in because the day where he doesn't have sara's back has not yet arrived and it never will. She's the woman in black - that much is clear. They kinda snark at each other during the fight. And holly shit it's fun. Then oliver wants to be noble and sara goes "whatever being Waller's minion taught you, I know better so get my sister and your brother out of here and let me handle them" and that's how laurel and tommy both find out who they really are. Sara tells tommy how much of a shady motherfucker his donor really is.
HIS DONOR LMFAO
I KNOW BETTER, SO ... could be Sara’s entry and exit line out of everything.
this also solves a lot of grief in the merlance thing. laurel and tommy keep going steady, tommy never gets insecure about her and oliver because oliver will be with sara. they all work out their issues, and maybe its slow and painful but hey - as it goes, everything is in place for ALL of them to live - because as it is sara will probably kill merlyn before the undertaking even happens.
so there. everything turns out better. outstanding.