Nasedo is a shapeshifter native to the aliens’ home planet Antar. He arrived with the crashed spacecraft in 1947 charged with the care of the Royal Four. In fact though, as Edward Harding he becomes predominantly responsible for Tess, helping her develop her powers and teaching her about her alien heritage.
While largely a protective figure, Nasedo’s efforts to assist the aliens often yield mixed results. Towards the end of the first season for instance, it is his assumption of the persona of Max Evans in Max to the Max that leads to Max’s capture by agent Pierce.
Much later, in Departure we learn that although he was a protector to the Royal Four he had also struck a deal with Kivar, the aliens’ nemesis on Antar. Nasedo would return Tess and Max’s son to Kivar and hand over the rest of the Royal Four. After his death in Skin and Bones Tess does her best to bring this plan to fruition without him.