Metaphor because you are comparing two things but not using like or as
In the first sentence, the "he" is a nominative as it is a subject.
In the second sentence it is an object as the form "me" is actually "I", but "i" is a nominative form and "me" is an objective form.
In the third sentence "Us" is also used in objective form as "us" is an object of an action by "my sister".
You don’t need and extra I but there Should be a comma
I hit my foot on the door, and broke it
