in a way rudy is as much of a pushover as asgore, but in a different way. he doesn't like to have the hard conversations. he's not willing to take any big actions that might affect his relationships so problems with those relationships never get resolved.
he wants to stay friends with asgore, so he doesn't confront him about his you-know-what, even though he should, in the process kind of enabling him.
i imagine he's tried to have a serious discussion with carol about her treatment of noelle multiple times. but they never go anywhere because he doesn't want to put a strain on his relationship with carol, and so he's never willing to push the issue very far. so they just do the same song-and-dance over and over.
rudy is like "Sweetie, we need to talk about Noelle."
and carol is like "What is there to talk about?"
"Come on, honey, you know what I'm talking about."
"And you know what I'll say. This is what's best for her."
"She's scared of you, honey."
"She's also safe because of me."
"She shouldn't have to grow up scared."
"At least she gets to grow up." and then rudy makes some kind of joke to ease the tension, and the conversation ends without anything getting resolved.
and, of course, he's not willing to have the hard conversation with noelle about the very real possibility of his death. he tries to broach the subject gently, she gets sad, and he just can't handle it, so he diffuses the situation with a joke like he always does. but because he's not preparing her for his death, it's going to hit her so much harder when it happens, because it will be out of nowhere.
he's in a position where he has the unique ability to strike all these problems at the source when no one else can. but he doesn't have the will to do it.
this isn't a rudy hate post, for clarification. i love rudy i think he's awesome. all of this is why i think and hope that he won't die in the coming chapters, but rather will just have a health scare / have his condition worsen. i want him to have the opportunity to change and grow as a person - and something like that, seeing what it does to noelle, that would be the perfect wake-up call for him to realize how his inaction hurts people, and gather the conviction to do better going forward.