Rayzen just wanted to ingrain in her the ability to evaluate danger and make an instantaneous decision to stay or flee in Sora. As such he decided to use the persona of Tobi, whose danger level was unknown due to Kamui, particularly the ability of his to phase in and out of space unconsciously, extended to either his complete body or parts of it.
He was satisfied on seeing that Sora understood from his reactions that something was wrong even before 'Tobi' stepped in.
And her decision to follow his order to run while at the same time, taking a moment to evaluate the enemy also impressed Rayzen. It showed how far she improved from immaturity that existed from her lack of experience.
Everything was okay until she fell for the provocation of ' Tobi '. Rayzen expected her to run without looking back, disregarding all sorts of taunts from the enemy. As only in such a way, would she have any chance to escape from the nerfed version of Tobi that Rayzen was acting as.
Hence his disappointment turned to anger for a moment, when Sora stopped just to question what happened to him, since it was an insult to his efforts in training her. He lost himself in his role as he tried to elicit a strong reaction from Sora, to battle it out and completely subdue her, to show her the mistake she made.
But what shocked him to the core was not her awakening her Sharingan, but the change in her personality that he was able to see clearly and her ability to lock him and the nearby surroundings in place.
...
After consulting with Chizuru and finding that Sora was just exhausted, just like the results of his diagnosis, he took her back to her home.
There he had to explain what happened to Sora to Takeshi and particularly Arisu, whose worries he took some time to appease.
Takeshi was extremely happily, in knowing that both his children awakened their Sharingan without facing any real tragedy. But he knew that the emotional trauma might still be there.
He had enquired with Toshiko what she experienced but she kept her mouth shut about it. And like Rayzen was left not knowing what to do about it. He was only able to give her some loose advices.
Learning of Sora's experience from Rayzen, he was worried about the other personality that barely showed itself. He decided to keep an eye on her, in case it turns out to harm her in the future.
His years of experience made him easily see that his both daughters were attached to Rayzen and he surmised that the trauma responsible for both awakening their Sharingan had something to do with him.
Rayzen was his nephew by blood. But he still saw him as his son. He neither supported nor impeded the growing connections between them, that transcended those of sibling love.
He was one of the heads of the conservative faction. And above all, it was nothing strange to marry within the family to preserve bloodline in the clan. Rayzen was his family, someone he trusted and groomed. Even though many may argue his bloodline being impure, to Takeshi, Rayzen awakening his Sharingan at a very young age was a testament to the purity of his bloodline.
Hence he was more than happy to have Rayzen marry his daughters. But that didn't mean he was heartless enough to force his wishes on his daughters. Such a cold side of his melted long ago, as he grew up alongside Rayzen when he groomed the latter.
Besides, how could he not know, that Rayzen already picked up on the clues. He knew that Rayzen had a childish side to him, even though he was mature and much more intelligent than him.
The childish wish of his to preserve what exists between him and the siblings, by ignoring their advances was plain for Takeshi to see. He just hoped Rayzen would make the right decision as always, atleast spare his daughters from the heartbreak. He as well as hoped that the current feelings of the siblings towards Rayzen would fade into something normal with time, so as to save them from a highly possible scenario of disappointment and heartbreak.
Hence Takeshi guessed that Toshiko's silence has something to do with Rayzen. If he knew this much, then nothing need to be said of how much Arisu knew.
Under Takeshi's advice she too abstained herself from interfering in their children's emotions, even though she wanted to encourage them. Nonetheless, even though Toshiko kept quiet she was easily able to pick up the scent of jealousy that was oozing out from Toshiko whenever she saw Mikoto.
As the family looked at the back of the leaving Rayzen, from the front of their house, each had their own thoughts about the boy, whose fate was closely tied to the family's.
...
Once home, Rayzen scrutinized what he had witnessed when he confronted with Sora.
Whatever ability that Sora used had locked all aspects of his Genjutsu in place, breaking his control away from his own genjutsu. Hence he surmised that this was a unique ability, that she brought about in her Sharingan and was restricted to illusions.
He was thrown off by the possibilities of her ability if it was extended to the reality as well. To a ninja, a second of hesitation means death, and a second of opening in the enemy's defence means an opportunity to kill them.
So if Sora was able to lock someone in place, that person will be at her mercy. Fortunately, for her opponents, such a scene will only happen inside a genjutsu. And a much powerful expert in genjutsu than Sora can easily break the genjutsu and escape from this plight. This was how Rayzen was able to escape. He was unable to take control of his genjutsu and had to spent effort to break the genjutsu he had setup by himself. And this was not the same as breaking his own genjutsu. He felt that he was breaking the genjutsu of another person.
Although he was surprised by this new ability of hers, this was still under the knowledge of what he knew about Sharingan and what he learnt from the records he had access to in the clan. Hence he was not totally spooked by Sora, the new and emerging freak in the family.