Admin Mawile: (*´ω｀*)) The answer is, at first, they do not take it well. 

Shuu:

-As long as you don’t try to interfere with his sleep, he doesn’t care too much what you’re there for. You’ll only become a problem if you make him do things, and until then, he’s content just to act like you’re not even there. 

Reiji:

-It irritates him horribly that his father thinks he needs someone to look after him, and he treats you with barely disguised disdain from the very beginning, finding creative ways to circumvent your supposed authority. 

Ayato:

-He outright rejects that fact that you’re supposed to be there as something of an authority figure, and torments you at every turn. He’s as bad as a bratty little kid… and completely misses the irony in that he acts that way. 

Kanato:

-He loudly complains from the very start, and is worryingly likely to react with violence if you try to do anything he doesn’t like. He does not like the idea that his father sent someone to watch over him, and openly says as much.

Laito:

-For the most part, he treats you with flirtatious advances and generally inappropriate behavior. Laito has about two settings when it comes to interacting with people, and you fall under the “target” one. 

Subaru:

-If scaring you off with violence doesn’t work, he gets horribly standoffish and grouchy. The idea that his father wants someone to look after them is beyond annoying, and he’s openly hateful towards your presence in the house. 

Ruki:

-While he’s hesitant to do anything to disobey his adoptive father, he also doesn’t like the idea that anyone like you has been sent. He’ll obey Karlheinz’s wishes, but it’s pretty clear that he’s not pleased with the situation. 

Kou:

-He acts friendly enough at first, but his personality can flip in an instant. As long as you don’t do anything he doesn’t like, he’ll treat you decently, but if you try to control him in any way, he gets dangerously upset. 

Yuuma:

-He’s not pleased at all with the idea that he needs to be looked after, and the only thing keeping him from reacting violently is that it’s his adoptive father’s orders. He’ll put up with you, but it’s clear that he’s not happy. 

Azusa:

-He doesn’t mind the idea at all, and actually seems sort of happy that you’re there. Of course, he does seem set on you hurting him (and doesn’t really take no for an answer), which can become a problem when you refuse. 

Carla:

-Horribly offended by the very idea that you present, he treats you about as rudely as is possible. He’s cold, unpleasant, and openly condescending, and treats you like you’re lower than him in every way imaginable. 

Shin:

-He’s more or less a nightmare to deal with, and makes more trouble for you than you could imagine. He finds it funny that you think you can control him… but is equally likely to get angry and violent when he’s annoyed.