In terms of the narrative structure of the novel, finally and for the first time, the reader comes to the astounding realization that (1) Dr. Jekyll and Mr. Hyde are one and the same person; or (2) Dr. Jekyll and Mr. Hyde are two parts of the same person, one evil and the other good; or (3) Mr. Hyde is a part of Dr. Jekyll, that diminished part that represents the evil in all of us. There could be other options in addition to the above, but these are the most traditional.
Likewise, in terms of the narrative structure, this information comes to us in the form of a long narrative set forth by Dr. Lanyon, but we should also be aware that Dr. Lanyon does not tell us everything: When Hyde has drunk the potion and has again become Jekyll, the two "old friends" apparently talked for an hour, but Dr. Lanyon writes, "What he [Jekyll] told me in the next hour, I cannot bring my mind to set on paper." Therefore, the reader does not yet have the complete story, because the timid, shocked, and horrified Dr. Lanyon is too stricken by the implications of Jekyll's story to even write it down.
We should remember from Chapter 6 that on the 8th of January, Lanyon, along with Utterson and others, dined at Dr. Jekyll's house; then on the 9th of January, Dr. Lanyon received the note from Dr. Jekyll (dated the 10th of December, an error of consistency on Stevenson's part), a note in which Jekyll, in the person of Hyde, pleads with his old friend for help; now we realize this will be a type of help which will finally bring Lanyon into direct contact with Jekyll's theories, which Lanyon has so long rejected. The direct confrontation will be in the person of Edward Hyde, with his sinister and evil ways. And true to form, Lanyon's initial reaction to Hyde is the same as the reaction of others — "There was something abnormal and misbegotten in the very essence of the creature."
