The person unnamed but if you want you can fill in the blanks. A little bit dark.
He stared at the man that had claimed Kathryn for his own. He had his arm around her waist and didn't hesitate to let everyone know that the only way they were going to speak to her was if they spoke to him. She didn't have a clue about the impression he gave everyone. She just thought they didn't like her for being with him, that she had lost her respect. He knew she was unhappy and that she wasn't going to stand for it much longer. He'd heard the night she had told him, told him that they shouldn't be together. That it was not fair on the crew. He'd then heard his response, a thundering crack of skin to skin. Her whimpered scream that shone with fear and shock. He raced round banging on the door, shouting for her to open it. It did open after a few seconds, but it wasn't on her account. It was his. He looked inside. He was sat calmly on the sofa, kathryn was no-where to be seen. He asked where she was and he said in the bath. So he stormed though to the bedroom quickly with him close behind. He knew he shouldn't do but he had to see her. See if what he had heard had all been in his imagination. As he stepped into the bedroom though his worst fears were deemed true. She was there. Tears brimming in her eyes. A gag round her mouth. Binds wrapped around pale bruised skin. Her dress she had worn earlier at the party ripped in pieces around her body. Speckles of blood surrounding it, those surrounded by even larger ones. How could he. He turned to face him, phaser drawn out in front. He turned to grab his own but he grabbed him pinning him to the floor. His knee pushing into his back. He wanted to make him pay, to make him suffer. Suffer like he'd made kathryn suffer. He called for security. They came quick. The stunned faces of Tuvok, his security team and Tom who had been near looked at the situation. Kathryn strapped to the bed in tears, Chakotay holding the other man to the floor harshly. They took the man. He told them to take him to the brig. They did so. He called for the doctor and with the help of Tom released Kathryn from her binds. She clung to him them in fear. Shaking. Crying. Tom stared in horror and anger as she tried to explain what had happened. Never once did she loosen her grip on him though. He clung back just as tight. He had to make her feel safe.