I shouldn't be surprised

[SpaceJB]

Full sentence is this "He's a big Meryl Streep fan, so I shouldn't be surprised that he's identifies with her character."
First, sorry, it's hard to describe whole context because this was a line from a TV show. it was very sarcastic.
I wonder what "shouldn't" means? I guess that its context is just "so I'm not surprised that~"
But what I learn is that "should" usually comes with something imperative or choices but it doesn't feel like it fulfill that criteria

 

[bushio]

It means something along the lines of:
"There is no reason for me to be surprised".

Imagine the following situation:
A person you do not like gets hurt, but at the same time you know it is not okay to laugh at somebody's injury. In such case, you might say: I shouldn't be laughing (it is not a typical reaction; there's no reason for me to be laughing).

Also:

"He's a big Meryl Streep fan, so I shouldn't be surprised that he's identifies with her character."

1) He identifies.
2) He's (he is) identifying
It's grammatically incorrect to say "he's identifies".

 

[Bondstreet]

It's another way of saying "I ought not to be surprised". "shouldn't" is easier to say than the abbreviated version "oughtn't", so it is often used instead.

forum.wordreference.com - rare-and-awkward-contractions-oughtnt-33781
.