Oz! He needs more interaction with Oz honestly, but Oz was one of the first people to greet him and that sticks. Likewise Oz is funny and makes funny and witty conversation and follows dialogue about mad villains and comes up with weird ideas involving bunnies.

All this endears him to Shark. Shark doesn't know him well beyond him being fun to talk to, so there's not quite a level or trust nor a level of protectiveness but he also feels Oz is a cool guy? He would be really willing to spend time with Oz doing whatever, because Oz is fun to talk to and seems generally easy to get along with.

Basically Shark likes Oz and has no objections to him at all. He's the kind of friend Shark doesn't know well but would be happy to get to know better. But because he doesn't know much about Oz beyond his fondness for rabbits and his sense of humor and friendliness, his impression of Oz is otherwise a little shallow that way. It's a very good impression, but once where he hasn't worked up the social link ranks affinity to know what Oz is like as a person beyond the easy going social chatting.