deep, deep-rooted, endless, implacable revenge.

"The morning after the night you saw me, I left my abode. I went to
London, and attempted to methodize my plans of vengeance. The first thing
to discover was Tyrrell's present residence. By accident I heard he was
at Paris, and, within two hours of receiving the intelligence, I set off
for that city. On arriving there, the habits of the gambler soon
discovered him to my search. I saw him one night at a hell. He was
evidently in distressed circumstances, and the fortune of the table was
against him. Unperceived by him, I feasted my eyes on his changing
countenance, as those deadly and wearing transitions of feeling, only to
be produced by the gaming-table, passed over it. While I gazed upon him,
a thought of more exquisite and refined revenge than had yet occurred
to me flashed upon my mind. Occupied with the ideas it gave rise to, I
went into the adjoining room, which was quite empty. There I seated
myself, and endeavoured to develop more fully the rude and imperfect
outline of my scheme.

"The arch tempter favoured me with a trusty coadjutor in my designs.
I was lost in a revery, when I heard myself accosted by name. I looked
up, and beheld a man whom I had often seen with Tyrrell, both at Spa and
(the watering place, where, with Gertrude, I had met Tyrrell). He was a
person of low birth and character; but esteemed, from his love of coarse
humour and vulgar enterprise, a man of infinite parts--a sort of Yorick--
by the set most congenial to Tyrrell's tastes. By this undue reputation,
and the levelling habit of gaming, to which he was addicted, he was
raised, in certain societies, much above his proper rank: need I say
that this man was Thornton? I was but slightly acquainted with him;
however, he accosted me cordially, and endeavoured to draw me into
conversation.