Constangreen

Helldragon is the slash ship between John Constantine and Gary Green 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!

Fandom
AO3

TUMBLR