Alaharel came from or at least lived in the Underdark for some time, studying magic at a university in his home city. At some point he came to the surface, which he found more exciting, and began adventuring.
About twenty to twenty-five years previous, he was joined by Jingle and her brother. After the death of Jingle's brother, Alaharel encouraged her to join the Alu-Lyth vigilantees for a sense of purpose and, presumably, family.
Alaharel had been helping the Guild for a considerable amount of time when, seventeen years ago, the former Guildmaster retired, and Alaharel was offered the position, which he accepted.
He has agreed to meet the party to discuss and possibly help train their magics, but these plans have currently been waylaid by the troubles in Alu-Lyth.
As he has not personally appeared yet, the party knows very little about him. One can assume he's a very competent wizard and leader, given his position and age. He also seems to be compassionate, as he suggested Jingle join the guild to help her heal from her brother's death, and agreed to help the party, as well as a guild of vigilantees that look out for the city and its misfits.