Dorian represents all of the doors in your house. Each door seems to have a slightly different appearance, but they are all named Dorian. There are officially 17 Dorians in the house, each willing to speak to you about the inhabitants in the room they "protect" if prompted through dialogue. He serves as the protector of the house, keeping out various miscreants in order to protect the player from danger.

Once you talked to all 17 Dorians he will be you're lover.