Who may enter a love relationship with Dorian? You can enter a relationship with Dorian only if you play as a male of any race. This means that the relationship is going to be a homosexual one. If you play as a woman, you will only be able to flirt with Dorian without any serious effects to relations with this character.
How to build positive relations with Dorian? During all of the conversations participated by Dorian (regardless of whether you talk eye-to eye, or with more characters ), pick the dialogue options that suggest support for mages. Apart from that, it is a good idea to respond with witty ripostes, which he is going to like. Also, remember to pick all of the dialogue options marked with the heart symbol.
Note - If, during the main storyline, you have allied yourself with Templars, Dorian joins the party only after you move to Skyhold. Regardless of the course of action, is VERY IMPORTANT that you express your will to keep him as your ally, during one of the conversations. Otherwise, he leaves for good and not only will you be unable to enter a relationship with him, but also he will be lost for the party.
More important steps:
- You need to build on positive relations with Dorian until the moment, at which a new quest appears in your log, as a result of a meeting with him (One Less Venatori). Complete the quest.
- The next quest from Dorian that you need to unlock is Last Resort of Good Men. It is necessary that you make sure Dorian accompanies you during the quest. After you complete it, meet with Dorian in Skyhold to talk to him about his sexual preferences. Your expressing your support for him should result in a kiss.
- You now need to unlock The Magister's Birthright quest, connected with an amulet that belongs to Dorian's family. Complete this quest, by taking the mage along.
- After you complete all of the quests from Dorian, you need to develop positive relations with him to the point, at which he invites you to one of private quarters in Skyhold. You will then have to make the most important decision, connected with this romance - either sleep with Dorian, suggest that you only want a platonic relationship or turn him down. In the last case, you irreversibly lose your chances of romancing with him.
- During the Wicked Eyes and Wicked Hearts main quest, you can play a short prelude to the affair with Dorian, i.e. dance with him in the Winter Palace.