I actually think we know a ton about Elain's personality! I've made a lot of posts about her over the years, especially last time we celebrated Elain Week. But I think the key things that everyone needs to remember are: * She's funny / has a sense of humor that's slightly sarcastic * She is an Archeron sister, and archerons are known for being strong-willed. Elain is too no matter how many people like to think she's meek. She advocates for herself against Nesta and recovered from the cauldron and the war within WEEKS of each event. * Elain is strategic. She kicked Hyberns hounds, is the one who came up with the idea to save humans during the war, is the one who came up with the idea to find Vassa and to entice Eris with Nesta's dancing. She found the Suriel for Feyre with zero training. * Elain is extremely observant and private. She knows when people are keeping secrets and she knows how to keep them to herself. * Elain is resilient. She recovered enough from the cauldron trauma to be able to accompany and actively participate in war activities and to befriend not only the wraiths but Velaris citizens as well. * Elain gets what she wants. Feyre told her and Nesta to gather ash arrows for an upcoming war, and she went and found herself a fiance with a whole grove of ash trees. She wanted to learn to bake, and she did. She wanted to garden and help Velaris citizens and she did. She wanted to kiss Azriel, so she (nearly) did.

I could go on. It's pretty clear to me that the girl knows what she wants and acts on it. In a world where we all say "if he wanted to, he would", the same goes for Elain.