JP LIKED Miguel? Miguel was a dick.

I haven't seen the whole movie in a long time, but I do see your point he was pretty much mean to them, like a bully and he said he would pray that he would met a very nice family. And I couldn't see why a family would want to adopt Miguel in the first place. Say if they had kid(s) and wanted to adopted another one, he would be a dick to them, or even to his new adopted parents I would think. I am going to have to watch this whole movie again and soon.

Miguel is just a really hurt kid. He's mean and angry for a reason.
And JP liked Miguel because he probably saw him as an older brother; even if Miguel had been with them for 6 months.
JP is also a naive little kid who doesn't understand that Miguel isn't very fond of him.

"Do you even remember what you came here to find?"

JP wasn't sad that Miguel left. He was sad that Miguel got chosen by a family and he (JP) hadn't.

Young kids are more inept and cocky. And I mean that in a good way.

They haven't fallen down or taken so much grief as older kids and people do.

They live in a sunshine world and reality hasn't hit them yet.

Therefore JP didn't understand that and hasn't had all the experience yet.

He's still bound and determined to cheer Miguel up try to make him feel better.

As you get older things become important there's more responsibility and reality and it is then you get tired of just trying to change someone realizing they won't change.

I've been there.