All the Gods will be surprised, with the exception of Tsukito, considering that Yui has never displayed this kind of cold behaviour before.
Loki: Loki will try to get Yui to talk to her, by doodling on her books and going as far as playing pranks on her. When Loki realized that he has made Yui even angrier, he will try to make it up to her by quietly placing a packet of sweets on her desk every day, until Yui finally simmers down and open up.
Baldr: Baldr will follow her everywhere, and he will try his best to get her to talk to him. Baldr will keep asking endless torrents of questions. Yui will eventually relent when she realized that she has made Baldr depressed and worried.
Apollo: Apollo will be upset, and he will try all sorts of methods to get Yui to talk to him. Apollo will even make the whole class to stay back to think of ways to find the cause of Yui’s distancing and brainstorm for methods to get Yui to talk to Apollo. (Apollo will involve everybody, basically). Yui will give in under Apollo’s endless apologies and his trademark puppy look.
Hades: Hades will immediately blame himself for the cause. He will spend hours thinking of what he had done to Yui that had made her upset. Hades will even distance himself from others, blaming on his misfortune. When Yui realize that Hades had taken the blame all upon himself, she will be forced to talk to him and explain the true cause.
Takeru: Takeru will stay away from Yui after noticing her ignoring him. He wouldn’t think much of her behaviour until one or two days later when he starts to miss her presence around him. That’s when Takeru will approach Yui and tries to talk to her. He will wait outside her dormitory every day as just being near Yui is enough. Takeru wouldn’t ask why and will wait patiently until Yui becomes herself again.
Tsukito : Tsukito wouldn’t have any problems with this at all, he wouldn’t even notice Yui’s silent treatment until the rest has pointed out her erratic behaviour to him. Tsukito wouldn’t mind, he would simply be himself and stay around her as usual. As Yui is the one who usually starts the conversation, the two will only sit around quietly. Until Yui finally couldn’t stand the suffocating silence, she will actually be the first to talk.
Thoth: Thoth will be surprised, especially when he had cornered her and Yui didn’t flinch in response and simply walk away silently. Then he will take upon himself to find out what he had actually done. The other Gods will actually benefit from this because Thoth will give lesser homework. Thoth will then actually make small snacks, corn food, specially for Yui when he saw her alone in the library. At times, he would even send Anubis to cheer Yui up.
Agree with some of these but Thoth’s is way off. Apologeticness? Remorse? These are not things that come to Thoth naturally, especially not from something as petty as being given the silent treatment. Oh no.
Thoth wouldn’t waste time thinking about what he might have done to cause such a reaction. That wouldn’t be his immediate interest. He’d be far more focused on the fact that she thought that she could refuse him, in any way.
And, really, the silent treatment? How quaint. He’d be more amused than anything else.
Then, he’d turn that great intellect of his towards examining her breaking point and he’d take the deepest, sadistic pleasure in tormenting her, and anyone else who crossed his path, until she finally snapped at him.
And, satisfied that he had “won” her attempt to challenge him, Thoth would scoff at her childishness and draw her out into an argument with vindictive glee.
Then, after the fact, perhaps he might be interested in subtly figuring out what he did that upset her, Thoth is nothing if not hungry for knowledge, and he’d tuck the information away in some mental filing cabinet under “action X causes reaction Y”. But that would be the end of it.
After all, why would he want to change his behavior when it produces such an interesting reaction from her?