The person with the higher status uses the word "I" less.
FLG found this fascinating because, just the other day, one of his newer coworkers was drafting an email to a very senior financial executive and asked FLG to review before sending. FLG's comment was to drop as many "I"s as possible. Sounded too submissive.
We use "I" more when we talk to someone with power because we're more self-conscious. We are focused on ourselves — how we're coming across — and our language reflects that.