Robert Blackburn Knight in A Man's Recovery from Traumatic Childhood Abuse describes dissociated memory loss in the form of ego states or "subpersonalities." Knight's abuse was particularly cruel and sustained and may be difficult for some to read, however he writes in a very matter-of-fact manner so it's easier to process. His therapist and he refer to his parts as ego states, not alters, though ego states that arose early to hold the trauma. These ego states shift over time, many splitting into two parts of the original ego state as therapy continues. Sometimes the original ego state, undivided, also returns alongside the split parts. He describes everyone's interactions in trance during therapy. There's little or no mention of them taking over in his daily life (executive control) or of their having discussions with him much in his head outside of trance. Knight's "ego states" have different personalities and genders and hold different trauma, but they seem to me slightly different from alters. But there's more in common than not.
Intrigued, I read the book too. It was published in 2002, and documents a therapy that began in 1987. The author wanted help for lower back pain that he suspected was partly psychosomatic. Once in therapy, his dissociative disorder was soon apparent.
In the preface the author mentions his diagnosis: dissociative disorder not otherwise specified (DDNOS), because his alters (usually referred to as ego states or insiders) do not take executive control. The author mentions that his main therapist intentionally talks only to him, about his alters, and he talks for and about them. However, when he has occasional sessions with John and Helen Watkins, they talk directly with his alters. The book includes mentions of the alters reporting trauma they experienced themselves, but there is no mention in the book of the alters taking executive control outside of sessions with the Watkinses. Toward the end, he does mention checking in with his "insiders" and getting their reactions on issues and negotiating with them, so they are having internal conversations. For some reason these are not reported in detail. Although passive influence is not ever mentioned, there is ample evidence of its presence in his behavior. The book describes DID-like DDNOS, as documented in a daily journal. There is relatively little reflection and analysis.
The book is loaded throughout with descriptions of sexual and physical abuse that will be highly triggering for perhaps many readers. The sexual abuse includes incest with both parents.
For me, strangely, although many other memoirs by men and women with a major dissociative disorder are highly triggering, this one was not.
Wikipedia: John G. Watkins