If you were to tell someone "I need you" because you might need their help or if they're your significant other, "Jeg har brug for dig" (I have need for you) is more appropriate.
How did you get so good at this? You're only level 6 but you're saying things that I haven't even heard of. Are you studying offline, by any chance?
Sorry for the late response, I haven't been on Duolingo for a long time. But DeadlyUnicorn is correct. I am in fact Danish. And they are further right in that I started taking the course because it was in beta, and I wanted to help out with potential bugs. But without the 'responsibility' to do so, as an Admin would have :)
Sorry for the late response. One other context that I can give you would be, "Behøver det at være så indviklet?", meaning "Does it need to be so complicated?". But I would suggest that you take a look at this site, since it goes much more into detail about the different "needs" that Danish has. Hope that helps you out. Happy Danish learning!