(TL;DR at the bottom)
In a relatively sparse room lies a journal on a table littered with alchemical ingredients. With all threats neutralized, the party reads the journal, hoping to gain some insight into the foe they’ve just slain.
The journal starts the day his (Zelarr) people became cursed. Out on a routine hunt to train the newly of-age young adults along with his younger brother, Alvir, they come back to the village in smouldering ruins. A humanoid in black robes and red trimming. greets Zelarr and his recruits, claiming responsibility for the ruins. The new recruits, including Alvir, attack head on before Zelarr can warn them not to. They are all subdued in a single blast of thunderous sound and the next he is frozen in place, unable to move.
The robed figure proceeds to kneel by each unconscious recruit, leaving bite marks on each of them. As it goes to kneel by Alvir, he suddenly lashes out with a short sword. Zelarr’s eyes are wide open as a claw comes out of the robed figure at an impossible speed and slashes Alvir’s throat before his short sword can touch him.
As Alvir chokes on his own blood, the life slowly fading away from his eyes, Zelarr struggles to free himself and save his brother, but cannot move at all. The robed figure takes out an orb and a misty substance escapes Alvir’s mouth into the orb. The orb then glows red, as do all the recruits and Zelarr.
Suddenly, the grip that held him releases and he falls to the ground. He feels a tap on his head: it’s the orb. The robed figure tells him that Alvir’s essence now resides in the orb and is linked to each of the recruits and Zelarr. To free him, he must create a special symbol of pure silver and sacrifice himself and all of the other recruits to restore Alvir to life. The robed figure drops a piece of parchment with the symbol and then disappears, leaving no trace.
You get the idea that the events were too traumatic for Zelarr, as his words grow increasingly obsessed with reviving his brother at all costs even if it means his own death. He reveals that he has the ability to control the recruits with the orb, who have upon waking up turned into werewolves.
TL;DR: Zelarr (the wood elf you fought) has his village destroyed by a mysterious figure that turns people into werewolves. The robed figure kills his brother, Alvir, but stores his essence in an orb. He steals silver to make a symbol that is supposed to bring Alvir back to life.