The Trickster in LotR

[Lathriel]

At first I was thinking of Sauron. However when it said

He doesn't know the difference between right or wrong

I thought of Gollum. he doesn't think of right or wrong. He only follows his own desires, mainy his desire for the ring.
Also he truly is a trickster. he tricked the elves of Mirkwood who held him prisoner. He also tricked Frodo and Sam when he led them into Shelob's Lair.