To judge whether there is a dependency relationship, we can't just look at college tuition. Legally speaking, if there is no de facto relationship between stepson and stepfather, stepson has no legal obligation to support stepfather. It stands to reason that the stepson has no legal obligation to support his stepfather, but his stepfather has provided him with college tuition. The obligation to support him is not only to pay alimony, but also to visit and comfort emotionally. This opinion is only made according to the description of the questioner, and the final opinion should be determined after specific verification of relevant facts. This answer is not regarded as the final lawyer's legal opinion.