Possession~
"I don't care if he is your childhood friend or not. I don't want him touching you. You are mine, and mine alone."
Luna nodded, "Alright I won't let him touch me, happy?" she asked and held his arms. Arthur's muscles relaxed a little as she nodded and agreed not to let Jacob touch her. He felt a flicker of satisfaction at her compliance, his possessive instincts somewhat soothed.
"Yes," he replied, his voice still firm. "That makes me happy. I just... I don't like the thought of anyone else touching you. You're mine, and I don't want to share you with anyone."