When the Cithaeronian lion was harassing the king of Thespius, the latter asked Heracles to kill the lion.Apollodorus, 2.4.9 The son of Zeus hunted it for fifty days and finally slayed the beast. The Thespian king entertained him as a guest in a brilliant fashion during that span of time, making Heracles drunk and slept unwittingly with each of his fifty daughters, including Heliconis. The hero having thought that his bed-fellow was always the same. Thespius intended this to happen because he strongly desired that all his daughters should have children by Heracles.Apollodorus, 2.4.10 & 2.7.8; Diodorus Siculus, 4.29.1 & 3; Tzetzes, Chiliades 2.221–225 In another version of the myth, the latter had an intercourse with Heliconis and her siblings for one week,Athenaeus, 13.4 with Herodorus as the authority seven laid with Heracles each night.Diodorus Siculus, 4.29.3, f.n. 51
