Well, let’s say because he’s in the SS, which indicates a higher level of commitment.

Lots of people joined the Nazi party for many different reasons. Some did to protect themselves because they had backgrounds that Nazis would crack down on. Some did to provide protection for their anti-Nazi activities. John Rabe, the heroic German businessman who stayed in Nanking as the Japanese force approached — fewer than twenty Europeans dared — and saved thousands of lives there, was a member of the Nazi party.

Belonging to the SS was another kettle of fish.

Well yeah. I just mean washed to the point he doesn’t recognize/care about his brother at all. Like the trope I expect to see is him being a brainwashed zombie soldier. I’d be delighted if you instead make him a human being still, who’s currently on the side we deem “wrong”. I just am predicting he won’t be fully aware/in control of his own actions.

Same Brute-time, same Brute-channel!

Well, he was already a Nazi, so I’m not sure how much washing his brain needed…