Warning! The following contains spoilers for the midseason premiere of Arrow. Read at your own risk!
Emiko Queen got her first real episode for Arrow's midseason premiere, where Oliver and audiences collectively learned the tragic backstory of this sister he never knew he had. As fans discovered before the break, Emiko is the daughter of Robert Queen and not-Moira, but now we know her upbringing was quite different from her half-brother's. The O.G. Green Arrow learned his father committed perhaps his greatest sin of all, and his mother Moira may have made things worse.
Robert Queen was at one point juggling two families, and he ended up abandoning Emiko and her mother to reconcile with Moira. He hadn't intended to leave them empty-handed in the event of his death, however, and wrote a letter asking Walter Steele to ensure his second family was taken care upon his passing.
Unfortunately for Emiko and her mom, that letter went undelivered, and Oliver and Felicity found it in a storage locker that belonged to one Moira Queen. That explained more about Emiko's family connection, but what brought her to Star City?
Vengeance runs in this family's blood, meaning Emiko is on a quest to bring her mother's killer to justice. Her investigation took her from the Glades to Oliver's hometown, believed to be where the person who killed her mother is/was operating. Emiko had a solid lead, and after some convincing from Rene, she accepted help from him and Curtis to bring the assassin down.
Unfortunately, Emiko actually had some bogus info, and while the guy she tracked down was criminal by and large, he was responsible for her mother's murder. Beside herself, Emiko was extremely upset at the thought of failing this mission, and by being back to square on in tracking the killer down. Rene was there to give her a pep talk, though, and offered his full-blown help, even if it meant breaking the law.
"My Name Is Emiko Queen" ended on the titular badass back at her father's grave, in the midst of an internal monologue that reasserted her drive to find the killer. She was approached by a mysterious figure, and viewers slowly realized along with Emiko that she was now unmasked-face to face with her half-brother Oliver.
It was big of Oliver to seek out Emiko and try to right his father's wrongs, but can he truly give her what she wants? After all, he's technically the property of the S.C.P.D., and with Emiko seemingly dead set on pumping a lethal number of arrows into her mother's killer, Oliver probably can't let that happen.
Will Emiko be satisfied with any help Oliver can provide, even if it comes at a cost of missing out on a "true" revenge Oliver's help at the cost of true revenge? Or will she tell her brother to kick rocks? If Emiko does the latter, there are other ways for her to get old school Green Arrow results without the actual Green Arrow.
Emiko has Rene firmly in her corner, and with Curtis hopping in to help in this mission, she could feasibly form a Team Arrow of her own. She's made it clear that she's not looking for a team at the moment, but should this mystery behind her mother's death get any deeper and more dangerous, she may not have a choice.