Wow - that's fascinating. And totally makes sense. There is so much difference in Riarios behaviour towards the two women and his behaviour towards Leo. I never noticed knowingly but the gifs alone are proof. Of course there are the looks too, but there is also something in his posture, when he's talking to Leo in the later seasons. And though I really like the idea of them being secretly in love, Riario just might have romantic feelings without further thoughts or expectations.
I have to admit that I never heard of the asexual spectrum before but it really explains tons of seemingly inexplicable facts.
Thank you very much for the pictures, the links and the recs as well. Surely I'll go through them as soon as possible. :)