User blog comment:Eobard95/Is Artemis the half-sister of Prometheus?/@comment-24152851-20170406092838/@comment-24152851-20170408103234

I'm not denying just how much control Prometheus has over Oliver's entire life, but that doesn't mean he's related to Evelyn.

Well yeah, they're both master marksmen, but so is Oliver and many other characters. There's a very distinct difference in their fighting style, with Vigilante sneaking up on opponents using his night vision googles before barraging them with bullets, while Prometheus tends to go for stealth shots from a distance with his throwing stars. Another point on them being different. Creators have stated that Vigilante's identity won't be revealed until next season, so unless Prometheus/Adrian doesn't get defeated by the end of season 5, that means Vigilante will still be around when Prometheus is locked up or killed.

It would make for nice symbolism, but still factors that make me doubt that. One of the main reasons is Evelyn doesn't seem to be aware of Prometheus' identity when they first teamed up. When she's with him, Prometheus still wears his mask and speaks through a modulator. If she's not aware of Prometheus' identity, then that makes it even less likely she teamed up with him due to being his family.