My family asked me to see a grandfather I didn't know since I was a child. Call and say something! I mean to say hello in advance and prepare to go there.

Don't call! I just don't know him well!

It's even weirder to call! You can ask your family to talk to him first!

Then, you can visit again! In reality, contact can be very close!

For gifts, you can ask your family. They should know better what he likes!