I will try my best to put all the things I've rambled at you into a cohesive thought
I've written Willa to find out about/meet Arator when he's about 18 years old, and by elf standards that's still very much a child to her. Why it took so long is for two reasons, one being that she's exiled, but the more pressing reason is that her Farstriders went to extensive lengths to keep it from her (bc of course they knew, they're gossipy sluts all of them and theres not really any bad blood between them and the Farstriders still in Quel'thalas). Willa is a lot to deal with on a good day, they did not want to live that life. They were mostly right, she didn't take it great and it definitely put her in a shit mood for the following few weeks.
Arator's existence is complicated for her. She feels incredibly hurt by him just existing at all, but then there's also a lot of guilt and unease around his living situation. There are a lot of 'what ifs' that she doesn't really know how to process attached to him. Nearly two decades later, it's easier for her to say she would have looked past his parentage and helped Alleria raise him (if that's what she would have wanted) but she knows that the past her could have just as easily fully rejected him out of pettiness and hurt feelings.
It takes a lot for her to even acknowledge that part of the guilt she feels about him is purely attached to the fact that there's a part of her that wishes he WAS hers. The rest is that he's just walking reminder that she turned her back on Alleria and it was a lot worse than she had even known about (because half her family being dead wasn't bad enough lol).
It also dredges up a lot of old anger towards Alleria, only now it's 'why did you have this child' + 'why did you have this child and then also LEAVE him'. It's the first time she can't fully understand a choice Alleria made, or it maybe that she doesn't want to because she doesn't want to imagine Alleria being so broken she'd abandon her own child.
Willa does fully acknowledge that Arator's whole life is kind of a shit show. She doesn't know how long he was even with Alleria, she does know he definitely wasn't conceived out of any kind of love, and he's a Windrunner so he's probably already cursed. Having Vereesa as his primary parental figure for most of his life is less than ideal to put it lightly. How he's even as adjusted as he is is a bit surprising. But for however much pity she has for him, she still does not want to talk to him.
Willa has a lot of regrets while simultaneously having no desire to think about any of them. He is a physical carbon copy of one of her biggest regrets. Willa thought she'd come to terms with and accepted all the choices she made because the repercussions of them were done. Her family is dead, her people were nearly wiped out, Alleria is gone. She's accepted all of these things and whatever role she played in them and they just need to stay buried and they don't when he wants to be around her and talk about it.
Part of her also thought that maybe she'd actually moved on from Alleria as well but she looks at his face and the only reason she's remotely tolerant of him is because he looks just like her. He absolutely benefits from the fact that she does still love Alleria and then he also feels like a good reason why she shouldn't because she just can't imagine it to be anything less than pointless now.
Being a part of his life also feels like she's overstepping. She has no idea how Alleria feels towards her anymore or if she would have wanted her to have any part of her son, and he is HER son, not Willa's. She knows that she has no right to play any kind of role in his life, but this is still Willa and she is still Like That so there's definitely part of her that has a hard 'if you didnt want me to adopt him maybe you shouldn't have abandoned him on the front porch' stance about it.
