Born to the noble Amell family, Daylen is the twin brother of fellow mage, Brienna. They showed signs of magic at an early age and Daylen was sent to the Circle of Magi in Kirkwall, while Brienna was put in Ferelden's Circle. The twins were separated for reasons unknown to Daylen and he never saw Brienna again.
Kirkwall's Circle was not always a nightmare. Or rather, it was a little more tolerable during Daylen's time there. But once he was recruited into the Wardens, things changed quite drastically and that was the prompt Daylen needed to return.
He joined the refugees of Ferelden's Blight in Darktown, serving as healer and a sort of defender of the people there. When he realizes just how terrible things are for the mages, he bands together with a few others and the Mage Underground is born. Headquarted somewhere on the Wounded Coast, the Mage Underground has made it their priority to free any and all mages who wish to be free and they attempt to make the Circle work the way it is supposed to for the mages who wish to remain. But as you can imagine, change is difficult when the powers that be rail against it and you are considered a fugitive.
As time passed, Daylen lost a little of himself everyday. He became almost fanatically devoted to the cause, to the point that he began approving of violent approaches to liberating mages. So you can imagine, Meredith wasn't happy with him. And he didn't rightly care.
He is not ashamed of his abilities, but prefers to keep them hidden. That is why he focused primarily on learning the arcane warrior abilities. He wields a sword and shield just as effectively as he does a staff.
Because he is so devoted to mage freedom, Daylen has little patience for social graces and even less patience for people he feels are wasting his time. No one in the Mage Underground is extremely close to him. They look to him as a leader, but turn elsewhere when they want companionship or friendship. Daylen may have very well forgotten how to be a friend to someone. He doesn't seem to care much either way. He is no doubt lonely, but his devotion to his cause has made him to largely ignore it.
As for his family, Daylen doesn't feel any sort of way about them. He barely remembers Brienna so he cannot say how he feels about her. As for his parents, he resented them for some time, but their misfortune has pretty much mellowed that out into indifference.