Constanqueen

Constarrow is the slash ship between Oliver Queen and John Constantine from Arrow.

Canon
2010

While secretly stationed as a spy on Amanda Waller's orders at Lian Yu, a returning Oliver learns that his camp is looking for something other than slave labour for their drug trade. Their leader is searching for something mystical and when Oliver's sent on one of the search missions, he happens upon Constantine, who takes him hostage and brings him into the 'cave of wonders' where the mystical artifact is located.

While in the cave Oliver questions how Constantine was able to do the things he did, Constantine simply explaining that magic can’t be explained. They come across a entryway that only the pure of heart can cross. Constantine handcuffs Oliver to keep him there while he goes inside. Oliver then unlocks himself and enters the room. As Constantine pulls the mystical object from the stone a spiked trap begins to fall from overhead. Oliver tackles Constantine to the side, and stops him from being impaled.

When they leave the cave Constantine tells Oliver he owes him one for saving him, but Oliver is still confused by magic. Constantine explains that the staff is a spellbook and he needs to keep it from dangerous people. Constantine offers to take Oliver away from Lian Yu, but Oliver refuses, since he wants to save the people being forced to work at the camp. He also can’t go back empty handed and Constantine gives him the top part of the staff, since it holds no magical power. He then uses the other half of the staff to transfer a protection tattoo from himself onto Oliver. Just as Constantine is about to leave, Oliver tells him he needs him to punch him in the face, since it needs to look like an escape attempt. Constantine punches him, then leaves.

2015

After Sara is brought back from the dead wrong, Oliver calls Constantine, calling in the favor he owes him. Constantine comes to Star City, and he explains that he needs to restore Sara’s soul to her body. He tells Oliver that if he had known that there were so many pretty girls in Star City he would have come sooner. An annoyed Oliver pulls Constantine from everyone. After prepairing everything for the spell, Constantine takes Laurel and Oliver into the spirit world to find Sara’s soul. Once they find her the spirit world sends attackers to stop them from taking Sara. Constantine tells Oliver to help Laurel get Sara, while he holds off the attackers. The three come back from the spirit world, Sara’s soul restored.

Oliver thanks Constantine for his help, telling him he owes him one. Constantine reminds Oliver that they’re now even, but Oliver says that they should just help one another when necessary. Constantine agrees. Oliver tells Constantine about Damien Darhk, Constantine telling him to be careful, and too leave town. With that he enters the elevator out of the bunker and leaves.

2016

John asks Oliver if Constantine could help them, Oliver replies that he's in hell. Thea asks what's going on with him, and Oliver clarifies that he means literal hell.

Fandom
AO3

Trivia

 * John Constantine was used to introduce Magic to the Arrowverse and Oliver