Sora, on the other hand, is...kind of a dick. And a pompous dick at that.
This is the one problem i have found up until now in the anime: since they are constricted by the time-limit of the episodes they cannot show Shiro and especially Sora in their full characterization.....
I'll try to explain for those that only watch the anime.
The siblings works under 3 rules that for them are absolute:
1) They are each other's WORLD. Their very existence is defined by the other one, the most important thing bar none.
2) Together they are utterly INVINCIBLE in any sort of game/challenge. Alone, they are almost unbeatable in their respective skills, and the other will come in to cover eventual weaknesses/cheats or to spring the trap that the first was preparing.
3) They DESPISE the world and humanity at large (although they admit there are exceptions).
This is their basic midset.
Other things you should know:
- they are perfectly ok with having sex with each other as soon as Shiro is of age (they are not blood-related). The appearance of Steph (and at least one other) seems to be pushing Sora into a possible Harem, with Shiro being ambivalent: on one hand, she doesn't want to be pushed to the side in Sora's world; on the other hand, she is ok with him having sex with at least Steph.
(the bath scene where Sora set up a trap to take shots of a nude Steph and Shiro intervene is quite different in the novel: there, Sora openly tells Steph that he will enjoy her nudity later. They are filming it and Shiro will check it later to be sure there isn't any underage nudity so that Sora can watch it)
- Sora isn't so much of a pervert or a
deliberate dick like it appear in the anime. For example, when they speak with Steph the first time he initially chastise Shiro for fanning the flames of a stranger's anger by being blunt when they are alone in a different world, then he suddenly realize that it's a perfect situation to MAKE an ally out of Steph. Only then he begin being a dick to provoke her into accepting the bet
- The fact that the siblings have problem communicating with others (especially Sora since he speak more) will become BLATANTLY CLEAR soon enough. They say what they think without caring if they offend someone. Sora at one point will
Spoiler:
say something so blunt and cruel to Steph that she will run away in tears and almost decide to cut them off despite being in love. When they point out to him that he went overboard, he will do his damn best to make it up to her by proving that the cruel thing he said was wrong, all the while denying that he is doing it for her. (Yes, Sora will act TSUNDERE toward Steph!

)
- When i said that Steph would become the chew toy of the siblings..... I WASN'T JOKING. You better get ready because she will suffer A LOT of humiliations because of both of them, although for the most part is played for laughs.
I think this little gem from the novel will explain it well:
Interrupting Steph who was speaking so eloquently, Sora placed a hand on her forehead.
"......Hm, it doesn't seem like you have a fever. What the- Steph, you just said something really smart!"
For some reason, Sora seemed terribly shocked.
"Is something wrong!? I, I'm sorry for not noticing earlier, I'll take you to a doctor immediately--"
"......Um, aren't you being just a bit far too impolite?"
Seeing Steph's shoulders trembling, Sora cried out.
"No, I mean-- it's you we're talking about, Steph!!"
"Yes it is, what of it!?"
Sora closed his eyes and shook his head.
"No, wait, wait, give me a sec, it can't be......"
He resembled a hardcore physicist who was seeing a real ghost right before his eyes.
Thinking, "This absolutely cannot be."
He swallowed painfully.
He spoke the incredibly hard to accept truth.
"I can't believe it, but......could it be.....Steph, you aren't actually an idiot!?"
Still harboring doubts, Sora cried out the inescapable reality.
The best part? He is partially JUSTIFIED in saying this!
