SPOILER WARNING: This article contains major spoilers for "All for Nothing," the latest episode of Arrow.
The Flash's Captain David Signh just stopped by Arrow. "All for Nothing," the latest episode, contained a flashback to the first time Dinah "Black Canary" Drake met Vincent Sobel, aka Vigilante. Seeing as both characters were formerly undercover cops for the Central City Police Department, it should comes as no surprise that Singh coordinated their partnership.
The flashback opened just as Vincent walked into Singh's office. Dinah, operating under the name Tina Boland, already sat in the chair in front of Signh's desk when Vincent arrived. The two exchanged a long look before Signh formally introduced them to each other and informed them of their assignment -- the same assignment that led to Dinah's Canary Cry and Vincent's original "death."
As played by Patrick Sabongui, Singh is a recurring character on The Flash, where he serves as Joe West and Barry Allen's superior. His last appearance was in "The Trial of Flash," where he testified in defense of Barry and stood up for his character. He later gave a speech celebrating the Flash's acts of heroism for Central City.
Starring Stephen Amell as the Emerald Archer, Arrow airs Thursdays at 9pm ET/PT on The CW. The series also stars Emily Bett Rickards, David Ramsey, Willa Holland and more.