Continuation of this post! I did not expect the amount of attention this post had in one month, and I’m so grateful that people are vibing with this idea. Also, the ramble continues!
So it would suck if child Tav only saw Astarion being mean, and I doubt a crush would last long this way. But Astarion would also do acts of kindness and camaraderie towards them. Letting Tav into some secret, making them promise to keep it with a finger to his smirking lips, Tav nodding and giggling in delight. Soothing Tav over a scraped ankle or knee after some rough play session. Tav getting lost and Astarion finding and guiding them back hand in hand. Tav bursting into tears over ruined clothing and scared that they're going to be scolded by their mother, so Astarion patches it up.
Tav crying and Astarion gifting them a handkerchief, on which he practiced his embroidery, just to calm them down. He might not think the embroidery is anything special, but to Tav it is the most precious gift of all. They spend all night staring at the handkerchief in wonder and fall asleep clutching it to their chest with a smile. And when they momentarily lose it one day, they burst crying because it was something Astarion gave them! And Astarion would just look at them strangely, because to him it is just a handkerchief, and why wouldn't they just get another one? But he would notice that what makes it so special was because it was something he himself gave them. So he helps them search for it, and sees how happy and relieved they are when they finally find it again.
(I'm playing with the idea that if Astarion regains some memories from his mortal life, that could be one of the first memories he regains of Tav themselves. He would have remembered previously instances where they are mentioned, because their sibling would talk about them constantly to an annoying amount, since they're their very best friend and did absolutely everything together. But he regains this particular memory, and he thinks oh, so this was them as a child. And he's struck by how much they loved him wholeheartedly from such a young age, and a lump forms in his throat at such tenderness.)
After a school recital with Astarion's sibling, whether it be music or theater, Tav being greeted by their respective families and Astarion. To their surprise, he gets on one knee and presents them a large bouquet of flowers, smirking at them. "To the star of the show," he says, and Tav could swoon.
("Where's my flowers?" would ask the sibling indignant.
"Get them from someone else," would deadpan Astarion, and their parents would stop the squabbling from getting too loud by giving the bouquet they got beforehand for his sibling.)
Tav keeps the handkerchief even as an adult. They got over their crush for Astarion, but now that he's gone it becomes a memento of that precious time of their life when they were a small child full of love for an older, charming young man. Two centuries later, they show it to a now undead Astarion during their trek to Baldur's Gate. And despite him seeing an amaturist embroidery an an old piece of fabric, he is secretly in awe at the fact that Tav kept something of his mortal life for so long.
If he decides to embroider them a new handkerchief, it is only because that little thing is out of style, darling, it simply won't do.
