The first time Danny flirts with Will, he thinks it’s a prank or a joke and laughs it off because he’s never been flirted with openly before. He doesn’t know how to recognize it and Danny is flirting with words, not touch so he can’t connect it to robin’s signals.
The next few times Danny flirts Will continues to roll his eyes and play it off as a joke because he doesn’t even consider that Danny could be interested in him. When Danny gifts him something artsy (think sculpture or scrapbook page) for the first time, Will genuinely tears up because no one that isn’t his immediate family has put this much effort in for HIM before. He’s gifted people his drawings his whole life and he has poured out his heart and soul into them and he never expected anything back in return. But seeing someone genuinely laying their heart open, sending a clear message with no ambiguity, unashamed and unhidden, trusting HIM to take care of their heart like he can be gentle, like he can be as soft and open as he wants and they will return it.
Someone—Danny—Danny with his charming way with words, his endless compliments, his awkward art abilities that has blossomed into a beautiful expression of his emotions—thinks he is worthy of this much effort and considers him good enough to give his art to.
I just feel like Will would be so overwhelmed in a good way when he is pursued and someone is chasing him, when he finally gets the love back that he so freely gives. But at the same time he’d be insecure because he doesn’t think he’s worth all this effort and he’s used to being the person doing the gifting so he’s really shy about letting Danny chase him at first.