Eren:
While it may seem all Eren does is obsess over Titans and complain over the Walls, he likes to spend as much time as he can with you. Normally since your days are filled with vigorous training and preparation, the two of you don't have much time together. But when you have time together, you like to lay around and talk about life. Eren often talks about what'll happen after the basement, and even promises to protect you and one day even marry you.

Levi:
As cheesy and unrealistic as it may sound, Levi takes you out when he has time with you. He hates the thought out ever losing you, so he makes sure to spend as much time as he can now. He will take you to coffee shops. Levi also liked to teach you how to fight better, and how to use your blades more effectively.

Armin:
Other than hanging around the library, Armin likes to borrow lots of books from the library and read them all with you. You two will discover new things, as well as have long conversations about the outside world. 

Erwin:
Erwin's the type of guy who sometimes just needs a break from the world. He likes taking you on trips outside the walls and having a picnic. You two will sit beside a lake, chatting until midnight, and eventually even fall asleep on his shoulder. Erwin hates to try to wake you up, so he attempts to bring you back on his horse while you're asleep. Not the easiest thing in the world.

Marco:
Whenever you two can manage, you and Marco sneak out to watch the stars at night. The two of you like to discuss your futures, and talk about the Titans. Sometimes you'll even just be caught off daydreaming at Marco's face as he lights up about his passions.

Jean:
We all have different hobbies, and Jean's and your hobby is certainly different. You two constantly compete to prove whose the best. The two of you will race to see whose faster, and even try to prove that you can clean faster than him! You will try to beat him in anything you can try, and the same goes for Jean.