I don't really know NCT Dream that well so you're gonna have to bare with me. If something doesn't match up to their personality then tell me in the comments. I'm also probably going to be doing this for all the subunits.
Mark
I think Mark would fall in love with you because of you being the tsundere type. He would be down for the chase and wouldn't stop trying until you said yes to going on a date him him. Once on the date he'd do everything to make sure you were comfortable. He would keep asking you out on dates until you eventually warmed up to him.
Renjun
He probably wouldn't understand at first, being one of the mood makers of the group, as to why you were being very distant from him and practically everyone except for your older brother Taeyong. He would finally understand after asking Taeyong why you were so distant and he would do anything and everything just to be closer to you.
Jeno
Jeno would probably just smile at you from across the room until you got up and asked what his problem was. When he said he liked you and wanted to get to know you better it flustered you. Luckily this boy was quick to start talking again, asking you some questions and whatnot.
Haechan
This prankster would probably pull a prank on you to get you to talk to him. After that he would ask you on a friendly date to get to know you better and for you to warm up to him more.
Jaemin
This lovely boy would probably walk up and talk to you without even thinking. When he felt you being really distant with answers he would ask you what was wrong. When you got up and walked away he would go to Johnny and ask what was wrong with you. After that day, he was more than careful as to not ask you personal questions but he kept talking to you until you got comfortable with him.
Chenle
When you first walked into the room, Chenle noticed something was off about your aura but he wasn't sure what it was. Of course, you being to younger sister to Taeil, it wasn't hard to figure out what it was. You were a tsundere. Something he learned from Yuta, someone you were also close with, was that it takes sometime for you to warm up to people. Chenle cautiously walked up behind you and tapped you on the shoulder and asked for your name and that was how a beautiful relationship started.
Jisung
This awkward boy wouldn't have a clue on how to get close to you. He would ask all his members and they would tell him the same thing, talk to you but, how could he do that. Whenever he walked up to you at school you turned a way from him and started chatting with your friend. Eventually he would walk up to you and just join in the conversation with you and your friend and that would ultimately end with him asking you on a date which you said no to but this boy wouldn't take that as an answer. He tried this everyday until you finally said yes.
Again I would just like to say, I barely know NCT Dream. If anything is wrong do not hesitate to help me out and tell me. I will fix it.