All 3 Uses

initiate
in
Invisible Man, by Ellison
(Edited)

And you recall how you plunged with the Founder, the Leader, deep into the black art of escape, guided at first, indeed, initiated, by the seemingly demented one who had learned his craft in slavery.
Chpt 5 *

initiated = introduced (to an area of knowledge)
It was as though I were being put through a fraternity initiation and found myself going back.
Chpt 6 *

initiation = a procedure or ceremony where someone is admitted into a group
They stared at me as the fellows had done when I was being initiated into my college fraternity.
Chpt 14

initiated = accepted into a group though a special ceremony

Definitions:

(1) (initiate as in: initiate discussions)
to cause (something) to begin
(2) (initiate as in: initiate into the art of drumming)
introduce to an activity or area of knowledge
(3) (initiate as in: initiate into the fraternity)
to accept someone's membership into an organization -- typically in a ceremony -- sometimes including a period of instruction and/or test
(4) (initiate as in: She is a new initiate.)
someone who has formally started in an organization, or been introduced to or attained some expertise in a particular field
(5) (meaning too rare to warrant focus)