Constangreen

Constangreen is the slash ship between Constantine and Gary from the Legends of Tomorrow fandom.

Canon
Gary meets Constantine when he and Ava seek out the warlock to help free Sara from the Death Totem's possession. Constantine doesn't specifically take notice of Gary, but does not treat him with the same derision as everyone else, but as a regular person. Gary's nervous, sometimes fumbling demeanour is in stark contrast to Constantine's confident, charismatic swagger, but a lesson in Gary's D&D adventures provides Constantine with inspiration to salvage their conundrum and he shows his gratitude by planting a kiss on a surprised, but ecstatic Gary.

After the mission, Gary invites Constantine to join his D&D group, which he does. Following the Legends' defeat of Mallus, Constantine seeks them out in Aruba along with Gary, whom he's been working with!

Fanon
Fans immediately began to ship the two after their first interaction. Many were pleased to find that the two were working together at the end of the season. The kiss between the two led to many people joking that "No one on Legends is straight". Although they had already been doing that for awhile. Fans also interrupt more comedic interactions between the two, since they are a very unlikely pair.

The ship gained more popularity on Tumblr and Twitter than on more fanfiction based site's. AO3 has little fic, although this is most likely due to the limited interactions between the two. Unlike other Constantine pairing between the two, fans were not looking for to their interactions beforehand, so fics were not written before their meeting. In their fics, they are typically a background couple for Avalance, but do have some that focus on just them.

On AO3 it is the most written ship for Gary and the third most written for Constantine.

Fandom
AO3

TUMBLR