5 years before...
Levi and Eren had been secretly dating for about 2 years by then. They managed to hide it from everyone the entire time. The two of them left the walls one time, Levi had wanted to try and help Eren get better control of his titan form. It was just the two of them slaying 7 meters, nothing important.
When they had cleared out the area they were in, they started to head back until Eren spoke up. "Levi... Do you ever think about how you might live if we ever get rid of all the titans?" Levi shrugs, "Not particularly, why?" Eren looks down and stops his horse, blushing slightly.
"I do. I'd like to get married and live near the ocean. I want my friends to live near me so I can see them every day. And, most importantly, I want to be able to wake up to you as my husband." Levi, having stopped his horse right next to Eren's, grabbed the brunette's hand. "We don't have to wait till the titans are gone to get married."
Eren looked to Levi in surprise for a few seconds until a smile broke out onto his face.
When they got back to the survey corps headquarters, Levi sought out Erwin and explained the situation. An hour later, Levi and Eren were secretly married by Erwin in his office. Erwin was the only one to know.
4 years earlier...
Eren sat up in bed and looked around. Everyone was asleep, or so he thought, so he got up and walked out of the bunkers, heading towards Levi's room. Armin opened his eyes, got up, and followed his friend. He had noticed that Eren had been doing that for the past year, and his curiosity was piqued. He followed Eren until he realized that the only used room in this area of the castle was Levi's bedroom.
Armin sped up and grabbed Eren's arm. Eren turned around in surprise, "A-Armin..." "What's going on? Why are you going to Levi Heicho's room?" Eren let out a sigh and turned away from Armin, knowing he had to tell the truth since Armin always knew when he lied. "I'm going to sleep with him."
Armin stumbled back, "W-What?!" Letting out another sigh, Eren clarified. "I've been married to him for the past year, I'm going to sleep in the same bed as him." Armin, to say the least, was surprised. "Please don't tell anyone. Amin nodded and headed back to bed. Now Armin knew.
3 years earlier...
"Eren." The brunette turned around when he heard Mikasa call him. "Ya, Mikasa?" Mikasa looked strait at Eren as if she was trying to peer into his soul, "You've been hiding something. I noticed you acting weird lately, and when I mentioned it to Armin he started acting like he was keeping a secret."
Another person who knew when Eren lied. "It's hard to explain, promise not to kill Levi." "What did he do to you?" "Just promises." Mikasa hesitated, pulling up her red scarf to cover her lips as she whispered, "I promise." "I'm married to Levi, It's been almost two years. Our anniversary is coming up is all."
Mikasa had to restrain herself from killing the midget right then and there. She stomped off in a rage, regretting her promise. Now Mikasa new.
In the next two years, Hanji, Petra, and Jean found out about the marriage, each promising to keep it a secret.
"'Till death do us apart,' I love you and I regret nothing." Eren felt his concious fading, only hearing part of what Levi said. "Eren... Love you... please... can't leave..." Eren wanted to say so much more, but time was short. He placed his hand over Levi's heart, "I never will." His lost thought before fading altogether was 'I hope he understood.'
That is all for this story. I might possibly continue it with an epilogue, but I'm still debating it. I don't own Attack on Titan.