N... not on a personal level. But you will be shooting at people with him, he will assume he is under attack, and if he is armed at that point he will shoot back. 


You understand you are firing on the imperial guard posse I have with me. Even if I wanted a few of them dead I couldn't know that was your intention nor would I know it's you. If you want to befriend oskar I would recommend some situational awareness and not shooting at him Ex: Oscar is heading towards the armory and the security codes have changed. Maybe you know them and help arm him or snipe the guards between him and the armory before you open it.