...in order to save E-2 Arrow. A crossover with "Flash" of sorts, as Barry and Cisco also appear in this fic. But it's mainly about difficult (weird?) situations - Oliver learning about alternate Robert Queen being the Arrow and the counterpart of Laurel being well... a villainess.

http://archiveofourown.org/works/9025231

Summary:
Oliver learns about the existence of Earth-2 and alternate Robert Queen being the Arrow. After finding out that his Dad's counterpart was outed and captured, he decides to travel to the alternate world in order to try to break him out, accompanied by no one else but... Black Siren, who agrees to help him in exchange for freedom. Written for supercode for a Christmas fic exchange.

Words: 9,760