Morpheus

Morpheus is one of the Oneroi, Greek gods of dreams. He is the embodiment of Dream itself. Brother of Icelus and Phantasos
First seen in Season 1.
A member of The House Of Erebus.
The Oneroi were sent to attack Clearwater and Fionn Corvin, their assuault via the medium of Dreams.
After Fionn Corvin killed Icelus and Phantasos, Morpheus wsa sent to kill Fionn in Erebus's throne room. He failed and Erebus called for Fionn to strike him down. Fionn refused, sparing his life.
Season 2.
After this Morpheus gave Fionn a gift: He allowed him to meet his father for the first time, encountering Lucifer in a dream and having a long conversation.
Morpheus held Erebus responsible for the deaths of his brothers more than Fionn, as he realized they had been willingly sacrificed by Erebus.
He became allies with Fionn and later, friends. He joined Fionn's Squad to avenge his brothers and bring peace to Tartarus. He fought in The Tartarus War.
Fionn asked him to join House Corvin as their God of Dreams and he accepted.