Ahaha, I didn't expect you to engage with the B/A slash! Even in such a short and humorous form.

Tsundere is a type of an anime female character who is both mean and sweet towards her love interest (often hiding her love behind mean actions.) So... people calling Avon this probably imply that's his dynamic with Blake? :D Which is huge oversimplification, of course, even if one likes B/A.