User blog comment:Bennlimos/Understanding the Zoldyck Family's Nen Situation/@comment-5780397-20151018161524/@comment-5780397-20151020121416

1) You are right about Killua being overconfident (of course, when the needle doesn't kick in), but he had also underestimated Biscuit's power at the time. Like... a lot. I think the inability to comprehend the true power of a Nen user is one of the main reason why Illumi put the needle in his head. I agree with all the rest, though. By "he didn't question it", I meant tha he did not try to understand how Alluka could use that power. However, Killua's trainig probably has little to do with Illumi, the only time the opposite was suggested was in the first movie.

2) Yes, but this is still a theory. We maybe he manipulates people, maybe he usescrafty plans involving his inventions.

3) That is another possibility, yes.

4) Again, there are countless possibilities. Kallut wasn't sufficiently skilled in other fields, or maybe he had already the ability to open his aura nodes without anyone teaching him, so learning Nen became his priority.

5) Same as 5. Depends on how the Zoldyck training work. Killua is said to be the most talented assassin in the family, they wouldn't voluntarily weaken him.

I don't have a reference right now, but I'm pretty sure Illumi did it when he touched Killua's head during their match, after paralyzing him with his aura. That is the point when he started to become fearful of other Nen users. He had no response to Netero using aura. If you look at the chapter where they discuss Killua's disqualification, Illumi moved his arm the same way he did with Killua when he realized Gon was too stubborn to give up on Killua. I think he was going to put a needle in his head, too. I'll look into it, though.

Thank you very much. Actually, since the series has been going on for a long time and does not have many chapters, it is easy to memorize some passages.