We've observed perhaps the closest thing to alien intelligence in the form of intelligent cephalopods -- like squids, octopuses, and cuttlefish. What surprises me about octopuses is how, despite a brain structure that diverged from our lineage perhaps billions of years ago and is vastly different from ours (they have a small central brain and enormously innervated tentacles each with its own local processing), they manifest what we readily recognize as affection and contempt for their human caretakers. They will nuzzle a favored human with their tentacles, and squirt water at a disliked human through their siphon. They do not need to be trained to do this. Either they are capable of experiencing emotional bonds broadly similar to ours and our terrestrial pets', or they are very, very good at faking it.

I didn't use to think this way, but now if we ever met an alien species, it wouldn't surprise me if we had enough cognitive and emotional common ground to establish meaningful relations provided they are carbon-based lifeforms or analogous.