Why does my dog act weird around me?

So I snuck my baby pup home a couple of years ago without my mom knowing, his name is Tucker. He slept with me the first couple nights. I have since moved out, but I come back to see family and him almost daily.

He acts weird around me. He sits in weird positions and almost acts scared of me.

(Oh and If it helps he’s half beagle and half blue tick.) When I come home he always wags his tail furiously and licks me and gives me cuddles and everything else. But sometimes when I walk in the room he’ll stop what he’s doing and just stare at me and not move at all. Like if he was scratching himself, he’ll stop what he’s doing and just watch me come to him and pet him and act timid. Oh and he only does this with me. My family keeps joking “what did you do that poor boy??” But it’s getting annoying because I’d never hurt him.

Whenever my sister and I fight he always breaks it up and always protects me over her. I don’t know if maybe it’s because as he sees me as his leader? I’m not sure.

I’ve tried looking it up but didn’t really find anything.

Anyone have any theories?