Supposedly he was to explore and document his findings-- recording everything around him in the new life form planet. That was until he realized there were living beings.

You, a mere merfolk who was classified as an 'alien' due to your webbed wedges between your fingers, and scales all around. Obviously due to being in another planet both you and him didn't know how to communicate.

He didn't like the water, he was scared. A big astronomy nerd yet he didn't want to trust you.