First, in the attribute descriptions for Charisma on page 5 Holmes says,
“Charisma is a combination of appearance, personality, sex appeal and so forth. Its most important aspect is leadership. A character of charisma below 13 can not hire more than 5 followers, and their loyalty will be luke-warm at best ~ that is, if the fighting gets hot there is a good probability they will run away. On the other hand, someone with a charisma of 18 can win over a large number of followers (men or monsters) who will probably stand by him to the death. Also a female with high charisma will not be eaten by a dragon but kept captive. A charismatic male defeated by a witch will not be turned into a frog but kept enchanted as her lover, and so forth.”
Second, in the TABLE OF BONUS AND PENALTIES DUE TO ABILITIES beginning on page 5 and continuing on page 6, there are no modifiers listed for Charisma. No maximum number of Henchmen, no morale of Hirelings, no reaction modifiers, nothing.
Third, the beginning of page 11 shows the HOSTILE/FRIENDLY REACTION TABLE. The table is very similar to the B/X version. The paragraph following the table says,
“The Dungeon Master should make adjustments if the party spokesman has high charisma or offers special inducements.”It is up to the DM to determine what adjustments are appropriate.
I find the description of Charisma to be interesting as it gives hints and ideas of what may happen if a character has a high charisma and also hints at some actual mechanics but I have been unable to find where these mechanics are given in the rules. A character with a charisma below 13 can not hire more than 5 followers and a character with a charisma of 18 can hire “a large number of followers” but, these mechanics are not spelled out beyond a couple of very general paragraphs regarding NON-PLAYER CHARACTERS given on page 8.
The Holmes Reaction subsystem including the impact of charisma is very open ended. In fact more detail is given in Men & Magic – Volume I of Dungeons & Dragons. That original rulebook had a table detailing the impact that charisma had on the number and loyalty of followers a character could employ. But I always find the qualitative examples given in the Charsima description regarding the female and male with high charisma to be fun and interesting.