Olaf's standards compared to the sinister duo

[vfds321s]

TSS is the first appearace of the sinister duo and it got me to thinking. The moment they reveal their presence, everyone including Count Olaf are shook in terror due to their aura of menace. This raises a question: why does Olaf fear these two? (and I'm talking about only in the books, not the Netflix series) After all, we've known him throughout the entire series to be a remorseless criminal who is all too willing to deceive, murder, burn, and blackmail to get what he wants. What have the sinister duo done that's so awful that even Olaf would not cross?

[Dante]

I don't think it's unreasonable to conceive of people who are even more evil and ruthless than Count Olaf; even a man like Olaf knows fear, but the sinister duo are scarcely human. Consider also exchanges such as that on page 297, where the sinister duo declare that, after kidnapping the Snow Scouts, "we'll burn down every single one of their parents' homes", and 'even Count Olaf looked a bit uneasy'; he has to declare that "the mainr eason we're doing all this is to get our hands on all those fortunes", to which Esmé agrees 'with a nervous snicker.' The implication seems to be that Olaf and Esmé are comfortable with being driven by selfish motives, and so by implication the sinister duo's motives are different, and somehow worse. They are evil for evil's sake. Olaf and Esmé only want to enrich themselves, but my interpretation is that the sinister duo want to see the entire world burn just for the sake of terror.

[Foxy]

I also think it's possible they are Olaf's older brother and sister, who maybe tortured him as a child.