From Online etymology dictionary
sequel: early 15c., "train of followers," from O.Fr. sequelle, from L.L. sequela "that which follows, result, consequence," from sequi "to follow," from PIE base *sekw- (cf. Skt. sacate "accompanies, follows," Avestan hacaiti, Gk. hepesthai "to follow," Lith. seku "to follow," L. secundus "second, the following," O.Ir. sechim "I follow"). Meaning "consequence" is attested from late 15c. Meaning "story that follows and continues another" first recorded 1510s.
