The daughter of the witch called Flemeth, Morrigan is a hardened mage a soft spot for jewelry and relics related to her mother. She tends to gravitate towards the cruelest conversation options available and hates helping people in need. She only sleeps with men, and she can teach you the Shapeshifter specialization if you speak with her about it.
You can give Morrigan a Golden Mirror that reminds her of something that happened in her past: Garin (near Diamond Quarter) at Orzammar Commons will sell it to you.
Optional Quest: Find the Black Grimoire within the Circle of Magi quest – it’s in Irving’s chest, found in the last room of the Senior Mage Quarters (right before the stairs to the third floor). Giving Morrigan the Black Grimoire will reveal Flemeth’s master plan for achieving immortality. Morrigan will ask you to kill Flemeth – but you’ll have to do so without Morrigan in your party. If you give the True Grimoire (found in Flemeth’s Chest) to Morrigan after the battle/negotiation, your approval with her will skyrocket.
Attempting to kill Flemeth is simply a bad idea, unless your characters are pretty well-equipped. You can prolong the battle by running in circles around Flemeth, or by constantly healing your tank character and yourself, but you’re better off convincing Flemeth to leave Morrigan be, letting you take the True Grimoire and avoiding the fight altogether. For this decision, you’ll lose some points with Leliana and gain some with Zevran, but you’ll keep your lives.
Regardless of your actions with Morrigan, she’s going to want to sleep with you at a certain point in the game (provided you’re a male character; otherwise she’ll want to sleep with another male character instead). This romance is integral to the plot and concerns the archdemon – but if you’re good, you can sleep with Morrigan normally before then.
Above: Straight sex with Morrigan
Above: Morrigan whispers sweet spoilers in your ears before mounting you