Mouse is another mage apprentice, trapped in the Fade after the Templars killed him for taking too long to complete his Harrowing.
Mouse will tell The Warden a bit about the Fade and its denizens. He will initially follow the Warden rather than becoming a party member, but if he is taught to assume bear form by the sloth demon found during the quest, he will become a controllable companion for the remainder of the quest.
- "'We?' I have faced more in this place than you can imagine. Fear is... just one more thing."
- "You hide from the big things, learn from the little things."
- "Simple killing is a warrior's job. The real dangers of the Fade are preconceptions... careless trust... pride. Keep your wits about you, mage. True tests... never end."
- The model for mouse (both here and in the Fade) is actually that of a rat.
- During the quest The Fade: Lost in Dreams, The Warden meets another mouse and can learn to shapeshift into this form. The mouse met in that quest appears to genuinely be a mage apprentice trapped in a dream and so is presumably not the same individual.
- What could give Mouse's lie away is that he wears a set of Senior Enchanter's Robes. This may be due to the fact Mouse is a pride demon.
- In light of new information regarding the nature of spirits and demons in Dragon Age: Inquisition, there is a possibility that Mouse was actually a spirit. According to Solas, a spirit often manifests as what its mortal viewer expects it to be. Spirits of wisdom are sometimes turned into demons of pride by this way, simply because the latter is the expectation. Following that logic, Mouse may have appeared as a pride demon to the Warden, when, in-fact, was not. The Warden deemed Mouse to be the true challenge of the Harrowing, which the Templars and senior mages warned as a demon. Therefore, Mouse adapted to the Warden's expectation. This theory can be supported by Mouse's choice to spare the Warden, whom it could have easily possessed.