Other uses of the particle に in お兄ちゃんには見つからない

I'm reading a story and two siblings are playing 'hide and seek'. The younger one, after finding a hiding place, says:

ここならお兄ちゃんには絶対に見つからないよ

ここなら means 'if here' that is, from the context, 'if I hide in here...'

The rest of the sentence, I can tell, have the general meaning of "if I hide in here, my brother will absolutely not find me". But breaking down the sentence to pieces... what is the role of お兄ちゃんには? お兄ちゃん is not a location so に has little sense (to me) when applied to it.

What's going on?

Thank you very much.