To be fair, being fictional means they're significantly less dimensional than real people and are incapable of holding secrets.

I mean there are real people I feel absolutely safe around, but they're just normal people I know and have built trust with. There are no famous people I can say the same for because I don't know them personally, even if they seem good on the surface. And for fictional characters like these, we "know" Aragorn is safe because he's written to be benevolent, we've read his entire life, and the author's dead so there's no possibility for new material to change that perception.