Eric is very responsible; like Gerald Croft, he's a womaniser, frequenting The Palace Bar, an Edwardian ''pick up joint'. There is every indication he's familiar with the prostitutes of the town, using his father's money to pay for them! He confesses that Eva Smith 'wasn't the usual sort' but he forces his way into her room and makes her pregnant.
The Inspector's verdict on Eric, or rather Eric's behaviour is that he 'used her for the end of a stupid drunken evening, as if she was an animal, a thing, not a person.' The use of the word 'animal' actually reflects Eric's own bestial behaviour, forcing himself on the girl. However, all the Birlings have failed to treat Eva as a fellow human being, 'as if she was.....not a person.'
His behaviour has been appalling but he does try to make amends: he takes money from his father's factory to give to Eva. However, she won't accept it when she discovers it's stolen. Also he is distraught by Eva's death and the death of his child.
When Eric discovers that his Mother and her Charity turned Eva away, in his grief and anger he blames her for the deaths; it is left to the Inspector to remind him and us 'each of you helped to kill her...Never forget it.' Unlike his parents, to his credit, Eric never will.