As much as I can see Melissa's 'I'm not weak, I can defend myself' attitude comes from, Nine does have a very valid point. All his life Nine lived as the black sheep of his family. He was cast away by his own kind only because he refused to hurt humans. His brother abused him and his clan degraded him as much as they like. In the end, he lost his tongue and fangs which absolutely disgraced him as a werewolf.
Melissa found him when he was at his lowest, extended her hand to a 'broken' Nine, and pulled him out of the darkness. She gave him hope and restored his honor as a werewolf by restoring his fangs and tongue with the help of yuri's magic). Just like that Melissa became his world. In a world where no one wanted Nine, she gave him his worth. He fell for her because she was strong, not because she 'needs' to be protected. He loves her because 'she' protected 'him.
Nine's loyalty to Melissa transcends the relationship between master and servant. He 'loves' her, so much so that he could kill his own brother. Though it's not in Nine's nature to harm others in any way, he himself confessed that if it's for her he'd be ready to walk into the depths of hell.
On the other hand, even though it isn't really Melissa's fault, she fails to recognize Nine's feelings for her as she constantly dismisses them as a part of his 'gratitude'. In order to protect Yuri, she keeps throwing herself away just as seen during her fight with Migen. I'm pretty sure everyone else also noticed how scared Nine looked when he saw her get bitten from the corner of his eyes. It almost looked as if his life got sucked out of him in that scene. Melissa at death's door stirred up so many emotions in him that he awakened his dormant powers and charged at Migen.
What she's doing now is repeating her method of 'I will throw my life away (even if I know I won't die) and save Yuri'. As I said, Nine loves her and even if he knows she will survive he hates seeing her in that state between life and death. Furthermore, he was the one ordered to serve the poison. Of course, he'd get angry, no one would be willing to hand poison to the person they love.
Do we love a strong independent fl who doesn't need protection? Absolutely, yes. But Melissa also needs to learn that her body doesn't need to be thrown away for every.single.cause. So, in my eyes Nine's worries and anger are valid.
I also just don't get why some people are calling him 'obsessive' when all he wants is Melissa's wellbeing.










HonEy~~~
MATTHEW'S GOD DAMNED SHOULDERS-
HIS-FREAKING-BROAD-ASS-SHOULDER.