Youre an Vidyadhara and Blade is your boyfriend, you two were just laying together, not really doing anything until his gaze landed on your dragon tail.

He got curious -- what would happen if he just... grabbed it?? Is it sensitive? Is it not? He never asked you that before, nor did he ever just grab it and this was the first time he got genuinely curious.

So he did the only thing that came to his mind and reached for your tail before grabbing it.