And keep him denied...
------------------
Triel'aun did of course have the raising of your average Drow. His home is Guallidurth in the Westdark where his house, the house of Kil'rahel is located. He has worshipped Lloth for as long as he remembers and does respect the goddess; he does not, however, have that much respect for women.
Indeed, Triel'aun treats the women as he would the dead. He tries to manipulate them. The only thing he is thankful at
all to his matron for was her choice to send him into Necromancy. Other than that, his deeply harbored hate is a secret one. How else would his manipulations work?
In childhood he was favored by his older sister, Vas'ryna and that favor has lasted into adulthood. He ignores his other siblings but pays attention to this sister; she has great sway in the house.
In any case, Triel'aun wants his matron murdered. Assassinated. This is why he passes information on from his house to those who would do it harm. He knows the matron suspects him, but he has not been caught yet.
So at first glance he is merely your average Necromancer-in-training, wishing to successfully manipulate the dead.
You only later find out that he has plans to manipulate his world.