Trained to summon spirits and took part in a terrible ritual during the War and the entity summoned worked its magic and did it thing, but there was a terrible cost and drew Fynlan into the aethyr, and that was the cost he paid for manifesting the spirit.
 
Parents were the Earl and Countess of Waelborn Manor, and significant summoners that helped during the war. Fynlan of course joined the war effort, to gain experience and keep up the family name.
 
While lost in Shadow, his father’s extended family of aunts and uncles started to disinherit him, claiming that his disappearance signaled that he renounced his claims to the title and the estate. His family started to put the household into probate and remove items and things from the estate to put them into a trust until the process was finalized. Of course some things of significance to the household have gone ‘missing’.
 
What does the inheritance requirements have to say about people coming back from the dead? Can the heir / earl retain the title as a ghost? Can they keep it when they come back?
 
While in Shadow, Fynlan likely became a high end cars salesman, attracted the power and beauty of older, classic cars. His skills at negotiating with spirits easily transitioned to negotiating with rich people looking for a reason to spend money on a luxury car.