Your 'first time' with them
Eren
Eren would do his best the first time. He would be cautious and would make sure that you're ready before he eased into you. He would want to be rough, but he wouldn't want to hurt you. Trying his best to help you enjoy yourself. Eren would leave kisses and love bites all over your body.
Armin
This baby would probably be more nervous than you, but he would try his hardest not to let it show. I can see him setting up candles, rose petals, the whole shebang. Armin wants the whole experience to feel like a dream come true.
Jean
Jean would be a flustered mess the first time. He would do his best to take it serious and would want to make it special. He just wants to treat you right, and not mess anything up. Also them hips, oh lord, his thrusts would be so smooth.
Levi
Levi loves you so much and would want to make this night as special as possible. He wants to give you the world, he treats you like a goddess, worshiping your body every step of the way. I know that he seems cold and rough, but for your first time together it would be soft with endless kisses and praises falling from his mouth.
Marco
Marco is another nervous baby, but he wouldn't show it. He would be so sweet to you. Leaving passionate kisses all over your body, making sure you're pleased. He wants tonight to be all about you and he would treat you so tenderly.
Connie
Connie would be nervous, laughing goofily a few times, but would want to take his time with you. He wants everything to be absolutely perfect for your first time together. He would like to treat your body like the queen that you are.
Bertholdt
Bertholdt would be so passionate and so gentle with you. He would kiss your neck while his hands roamed your body, making sure he pays attention to every part of you and your needs. He loves for you would be shown in every thrust and sex with him would be so romantic. He would do anything you asked him too.
Reiner
I know everyone thinks Reiner would be kinky and rough, but not for the first few times. He would be extremely passionate but gentle. He would ease into you and would take his time. He wants to make you feel like a princess. He would caress your cheek and whisper sweet nothings in your ear.