Steve Rogers
When you gave him a chance. He had already fallen hard for you but you didn't want anything to do with love because of the bad things that happened in the past. It took three long, agonizing months before you even agreed to one date but that one date was the one that changed your mind about love. He was nothing but a gentleman, kind and courteous with a lovely smile to match. He had admitted to both Nat and Clint that he was head over heels in love with you but you wouldn't give him a chance. Their advice? Keep trying.
Tony Stark
When he listened to your story and couldn't focus on it. Tony is self-centered and an egotistical asshole to a lot of people, most of the time but that doesn't mean he's heartless. He listened to everything you told him but when he met you he couldn't focus on a word you were saying because he was trying to figure out ways of keeping you around him so you would fall for him as he had for you. He's a very smart man and you knew that but you couldn't help yourself when you fell for him, he was there when you needed him most and that meant a lot to you so you gave him a chance. Neither of you regrets that.
Bruce Banner
When you didn't leave when he Hulk'd out. He tries, gracious he tries to keep his anger under control but sometimes it doesn't work and the other guys decide to ruin everyone's day. He didn't realize what was happening until afterward when he was told but he took quite the liking to you when he found out you stood your ground against Hulk. Hulk seemed to like you nearly as much as the doctor did and the more you talked and laughed with Bruce the more he fell for you until he finally got the nerve to ask you out. It was one of the best days for both of you.
Thor Odinson
Once he looked passed all of the trivial things and got to know you from the inside out. Honestly, he thinks you are beautiful but his mother taught him to get to know someone first before judging them and that is what he did. It only confirmed what he already knew, that you were indeed beautiful inside and out. He admitted to his mother that he loved you very much before he dared to ask you to be his. You had never accepted something quite as quickly.
Loki Laufeyson
You stuck by him. There have been many times where Loki believed he was truly alone in this world but you had always been there to remind him that he was not and to keep him grounded. You were like him and unlike him all in one. You were sassy but sweet, you were everything he ever looked for in a significant other and it didn't take him long to make you his.
Clint Barton
When you hugged him. You were both having a particularly bad day, neither of you was feeling great, and being reprimanded for a failure that was beyond your control didn't make it any better. You were listening to Clint complain, something you did not blame him for, about everything that had gone wrong, and how angry he was. You don't know what came over you but you hugged him, a long hug for every problem. You didn't realize how much it meant to him and how flustered it made the archer and assassin. It took him a few weeks after that to ask you out and you certainly said yes!
James "Bucky" Barnes
When you refused to give up on him. He felt like a hopeless, lost cause, and even he was ready to give up on ever remembering who he was but you didn't. He didn't know who you were or why you were trying too hard for him but each time you could you would tell him about the past and tell him that he was the reason you tried so hard. That the man he was, was still hidden inside his head somewhere and you were going to help him find him. No matter how much rubble he was under or how deep it went, you were going to stick around until then. He realized, after a long night of pacing and frustration, that he cared about you. He couldn't remember who he was then but that didn't matter because the person he was now both loved you. He woke you up to tell you that he did and if you would give him a chance. You didn't think twice about your answer.
Sam Wilson
When you smiled at him, laughed with him, truly opened yourself up to him. That's when he fell in love with you. He thought you were beautiful from the first time he met you and wanted to get to know you. The more he did, the more he fell in love with you. He knew you were reserved and he accepted that so when you began to show him the real you behind what you showed others he got to appreciate more of you. Love more of you. Something so private you let him see and he loved being that special person for you. He loves you and there is nothing in this world that can change that.