#the bare minimum

If you go to anime/gaming/sci-fi/furry/etc. conventions, then you already know this one. If not, it's a guideline to take care of yourself during the con. It's also helpful outside of cons, especially when you're in a situation where you're really pushing yourself, when you're in "survival mode," or when life is hard and demanding a lot from you. Keep in mind that these are bare minimums, although they can be somewhat adapted for your needs (i.e. if you shower every other day, or if you've got a newborn and an uninterrupted 6 hours of sleep isn't going to happen).

They always remind people of this, at least at the anime conventions I've been to, because it's easy to get caught up in the moment and forget your basic needs during what's a frankly quite physically demanding event, and then you wind up exhausted, burned out, possibly in a flare-up, grouchy, con-funky (if you know, you know)...it's just not good. Also keep in mind that these are meant to get you through something: a con, finals week, a difficult time, whatever it is; you ideally don't do this bare minimum plan forever. When and if you are able to do so, give yourself more.

Lately, I've seen a couple of discussions centering on Lily and James (and Severus), in which people claimed that joining the Order of Phoenix was the bare minimum James could've and should've done. A very similar argument crops up, when it comes to why Severus joined the Death Eaters. In his case, it often boils down to "What else could he have done?" and "Most people in his situation would have joined the Death Eaters, too."

Personally, I don't think these arguments work. They can't work, because they expect that they had to choose between joining the Order or joining the Death Eaters.

Which is flawed in and of itself, because those aren't the only options. They are not even the normal options - they are the radical ones.

At their cores, both the Death Eaters and the Order of the Phoenix are anti-state terrorist organizations. They operate outside of laws, work in secrecy and are willing to use (lethal) violence to achieve their goals.*

And, on average, most people just don't join organizations like that.

They either keep their heads down, try to stay "apolitical", form civilian groups that operate within the laws, or join governmental organizations.

For James, the bare minimum wasn't to join the Order of the Phoenix. The bare minimum was to do no harm. The bare minimum was to love Lily, to support her and to be by her side and protect her, if needed. Apart from that, the only "bare minimum" that should be required is the bare minimum that is true to all relationships: pull your weight in the relationship and don't be abusive to your partner. (And while James was abusive towards Severus and a jerk towards Lily during SWM, he was also fifteen or sixteen during that time and the books state that he matured at least somewhat after that. So it's completely possible that he did fulfill that requirement.)

Joining a militant organization to fight for the rights of muggleborns exceeds this bare minimum. Most students, who went to school with him, didn't do that. Most people probably kept their heads down. Even if they were anti-Death Eaters, they might voice these views, but they wouldn't fight for them. (And they might not voice them either, because Death Eaters attacked civilians over this!) And if they wanted to oppose the Death Eaters, they probably joined the Ministry instead.

So James joining the Order - whether by joining together with her, inviting her in or following her - is actually a pretty big deal. A lot of people - including completely fine and loving people who were probably far nicer than him - would not have done that.

And a similar thing is true for Severus. When people say "most people in his situation would have joined the Death Eaters, too", that's just not true.

The only way you can come to that conclusion, is when you ignore all the decisions he has made prior to SWM. I mean ... yes. An abused teen who gets bullied at school, who denies the hate crimes committed by his friends, who heavily sympathizes with an anti-state terrorist organization that targets his best friend and people like her, and who just fucked up his relationship with said friend (who was the last person who kept him from joining up) ... will probably go on to join said anti-state terrorist organization that targets his (former) best friend and people like her.

But Snape made decisions before SWM.

Because, let's face it: Most people will never even think of the idea of joining an anti-state terrorist organization, especially if said organization is targeting their friends. And this does include most people who are abused at home and/or bullied at school.

Severus isn't most people. He decided to become friends with Mulciber and Avery. He also decided to excuse their behavior. He decided to listen to propaganda (despite having a friend who was directly affected by that). And he probably decided to join up, long before SWM happened.

So what could Severus have done?

The bare minimum. No, he didn't need to join the Order and fight side by side with his former bullies. But he could've refused to do harm.