EreJean

EreJean is the slash ship between Eren Jaeger and Jean Kirstein from the Attack on Titan fandom.

Canon
The first two interacted when Eren mentions about joining the Survey Corps, Jean interrupts Eren's conversation by calling him nuts for wanting to joining the Survey Corps, as during that time it had the highest fatality rates. Eren answers back to Jean telling him if he was joining the Military Police to have a nice easy life, Jean agrees with Eren and tells him he's just being honest. Jean continues to tell Eren that being a Military Police officer is much better than trying to act 'tough' as Jean thinks Eren might be afraid. Eren stands from his seat where Jean does the same, the two face off to what seems it might start a fight until the bell rings. Jean apologizes to Eren and tells Eren it's best to let it go, Eren agrees and the two head off. Following behind Eren is Mikasa, Jean spots Mikasa and compliments her before she heads off with Eren, Jean begins to follow her until stopping he sees Eren and Mikasa together, Jean is shown to have a grudge against Eren after this.

A few nights later the two get into an argument again, this time it was due to Jean joking about his technics when it comes to the ODM gear, which very much angers Eren. Eren grabs the hem of Jean's shirt before being stopped by Mikasa, Jean becomes jealous and loses his temper. As the fight begins to get physical, Eren grabs Jean's wrist before slightly beginning to push him and kick his leg, which flips Jean making him hit the floor very hard.

Fanon
It's one of most slash ship for the two, with Eren's coming in third and Jean's coming in second on AO3