Alec and Robert always had their tension. Not that they didn't love each other, they had entire different ways of was soft and gentle, rather protect than kill. Robert rather be right up in the front lines. Alec was able to think in different ways, Robert could only think in the code of a shadow hunter. And if you did not kill demons, you were not a shadow hunter in her father's eyes.

That's why Alec had such a hard time gaining respect from his father. Even though no one spoke to Robert about Alec's fighting style, Robert somehow knew. He knew that Alec was no fighter, no true shadow hunter. Alec did not like to kill, and that has shown through since he was little.

Most of the family always thought that Alec was meant for something else, not that she was saying her brother could not fight. She was just saying that he didn't have the heart for fighting and killing. He didn't have the heart of soldier. But, he could fight, this she could promise you.

Robert lived and breathed to fight the good fight. To fight against the dark worlds and to keep the human race safe. Robert, like Isabelle and Jace, were built perfectly to fight. From the structure of their body to their "tough skin" personality. Fear did not come easily to them. Because they are ready to die for the cause.

Alec would lay down his life for his friends and family, but to truly lay down his life for the clave? No, he respects the clave but he does not live the code like the rest of them. He doesn't break rules, but he doesn't force others to follow them. Not that they would listen to him anyway, her and Jace. That's why he tagged along, to give their group a conscience.

Considering all this, it was a surprise to everyone when Robert allowed Alec to use his own weapon. Robert, who was the exact opposite of Alec, seemed to have a new found respect for him. Robert, despite what everyone thought, didn't frown upon Alec as much as everyone thought. In fact, he respected him for his differences. Because, he too, was a protector at first. And now he a force to be reckoned with. And Robert knew more than anyone else what Alec truly was: and he was a force that will surpass even him.