Adan is the apothecary at Haven.
Adan claims he is serving as a healer somewhat reluctantly, as he sees himself as more of an alchemist who creates various types of potions. When asked why he is so cranky, he claims that he is not able to offer "comfort" to patients as a real healer like Mother Giselle.
According to Elan Ve'mal, he had at one point served the King of Ferelden and left said service "when there was no longer a king to serve".
Adan is responsible for the Apothecary where the Herald may upgrade and equip potions (though he is unable to upgrade them until the Herald brings him the apothecary notes found in the cabin west of Haven). Adan claims he helped the Herald recover from the effects of the Anchor following the Breach at the Temple of Sacred Ashes.
During the assault of Haven, Adan becomes trapped with Minaeve under a burning cart in front of the apothecary. If the Herald fails to rescue him on time, the cart explodes and he will die. Even if he lives, he does not serve as the apothecary at Skyhold and can be found standing around in various locations.