Sequacious is formed from the Latin sequac-, or sequax (which means "inclined to follow" and comes from sequi, "to follow") and the English -ious. The original and now archaic meaning of sequacious was "inclined to follow" or "subservient." Although that meaning might as easily describe someone who willingly dropped into line behind a war leader, or who was unusually compliant or obedient in any sense, the concept gradually narrowed into the image of someone who blindly adopts ideas without much thought. Labeling a person sequacious is not very complimentary, and implies a slavish willingness to adopt a thought or opinion.
Word History
Etymology
Latin sequac-, sequax inclined to follow, from sequi