In a story I am writing, there are two characters that for which I need motivations. One of them knows that their sister is dealing with an eating disorder but doesn't tell their parents because.... I don't know. And another character witnesses his friend assaulting a girl while drunk but never tells him or anyone else... for some reason. So, what should the motivations of these characters be? I don't want these people to be one-dimensional and have no reason to do this, but I have no idea why anyone wouldn't say something so I'm a bit stuck. Help is greatly appreciated.
The former feels realistic. People don't tell other people--even (or especially) close people--about mental problems. They're shameful. The latter feels UNrealistic. There is a powerful societal taboo against violence against women, and it is enforced by men against other men, usually through direct physical confrontation. Basically, realistic reasons for nonintervention include: A) wow, she really had it coming, or 2) this guy is a serious coward. I guess there is also C) as assaults go, this was something trivial and harmless. I'd say it's also possible that the guy is just very loyal to his friend? Except that being loyal to your friend would seem not to imply keeping secrets from your friend. I dunno.
Yeah, that's the problem. He needs a reason not to tell his friend that he does this... which is the thing with which I need help.
I was thinking something like loyalty. Like it was something he saw that he really didn't want to believe his friend was capable of, so cognitive dissonance took over and he doubled down on his belief that his friend is a good guy and convinced himself that it wasn't what it appeared to be.
That assumes that he knows that the friend doesn't remember. I think that it's logical to assume that he thinks that the friend does remember and that the friend is just not talking about it. If he witnessed the assault, did he do anything about it in the moment?
The former is realistic enough, When you have ANY type of Disorder, You'll always be shameful of it. Be it depression, or an eating disorder. (Which in all likelihood causes more problem for themselves since they never try to get any help for it then) While the latter, I mean. If they are good friends, I could see him not saying it to anyone else, But he'd definitely bring it up to his friend. And if they weren't good friends, I mean... He could be afraid of if he found out? It all depends on the personality of the guy in the end. He could be a coward or a jerk, who just wants to stay out of things that isn't his mess.
Both of those reactions sound realistic to me. People don't want to rock the boat, and people don't want to burn bridges. If someone's aware of a problem, but no one else is making a fuss about it, the temptation to just stay silent can be huge. After all, you don't want to go throwing around such severe accusations if you might not even be certain, right? And it's so easy not to be certain. This is a great opportunity to explore some really stressed, twisted thought processes. "Did I really see what I thought I did? How many drinks did I have? Was it really as bad as my memory is making it out to be? Maybe they were just flirting. Flirting really aggressively, with her telling him to stop. But my friend's a good guy, so he wouldn't do a bad thing, so the thing he did must not have been bad, right? And if she's not complaining, should I really be raising the issue on her behalf? Maybe she wouldn't even want me to, and I'd be hurting her by talking about it." It's cowardice, but of a very common and natural kind.
For the eating disorder, he may think that it's something it's not up to him to bring up because it's so personal. Depending what their parents are like he may also be trying to protect her from them. Some people's reactions, though well meaning, are not helpful to those situations. Especially if he thinks the parents are controlling and may have contributed to the condition in the first place. I agree that it is harder to justify the second one because protecting his friend means he is complicit in something really awful. It could be they are actually a bit scared of their friend, or that they panicked and froze in the moment and then feel like they can't do anything about it later without incriminating themselves, or shut it out and go into denial because of the guilt. They might, as @The Dapper Hooligan says, he may convince himself he didn't see what he thought he did.
I think the answers to your questions, especially the second one, is to get to know your characters and the situation a bit more. Are you writing your story already, or just thinking about it? If you haven't written these scenes where the situation becomes apparent to your character, write it. What you write may well give you clues. The background to your story's characters (main and secondary) will also matter. I think the best solutions will come from you and not from us. I can think of lots of reasons somebody might stay silent, but it's the one that YOU choose that matters. Push yourself to make a decision. And write the scenes. While the character is watching the assault happening, what is he thinking? Does he think the assault is out of character? Does it bring up an aspect of his friend that he wouldn't have believed? Or does it confirm something he's always suspected? Don't go for the most obvious answer here, or at least not till you've thought of other answers as well. A story where a character is conflicted or hard to pin down is more interesting than a story where motives are plain. What is your POV character's attitude towards alcohol? Does he believe it loosens up the inner wishes and thoughts people have, which they normally repress? Or does he feel it makes them do silly/horrible things that they would never dream of doing while they were sober? All of these things (and more) will factor in, especially as he's watching the assault take place. And that's just his side of the story regarding the actual assault. What is his normal relationship like with his friend? Is he a little afraid of this friend? Has his friend ever been in trouble with the law? Does your POV character think his friend is too timid or gentle to ever do something like this? And etc. Push yourself to get to grips with YOUR character, not to look for some outside source of motivation. Find that motivation within your character, and your story will take off and fly.
Maybe he doesn't trust that they wouldn't make it worse? Today's attitude towards sexual violence is "Bros before hoes." Even if the character does recognize that his friend's action wasn't just "boys being boys," he'd probably know how many other people wouldn't recognize this and would take the side of his friend while blaming her for being "seductive."
