My dog keeps barking outside my door and scartches it?! And its 3:30 am?

I jut got this poodle5 days ago. Hes 2 years old. I asked the owner about him, and said he never barks at all. But aehile ago at around 12am, i went to the living room to pat him. Today was actually the first time he gave me a response, because for the past day he ignores me alot. But i am pussed that he keeps barking for long now. I dont know wht to do. He even went 2 stairs up and my sister told me so i have to get her and put her down to the living room