"Yenne's only goal is to screw with people, so you shouldn't really talk to him if you can avoid it."
Yenne is the outcome of when Vortex and X in the future corrupts Zuka and sends their creation back in time to help vortex win the war. He is not trustworthy and (as 100miles says) only has the goal to screw with you. He seeks to replace Vortex after setting up RIFT and X to get X killed. Yenne's name translates to "talker" and he can easily be referred to as a Jackass Genie since he messaged UnownDB saying he can ask him three questions. Yenne is not an original idea, he is the 13Xs equivalent of Sliske from Runescape. To trust what all Yenne says is not a good idea, however there is truth to some of what he tells you. However it may not be stuff you don't already know so if you ask him anything, make sure you already know the answer to your question.
He is an unreliable source of info and despite 100Miles' warning, RIFT has the tendency to talk to Yenne whenever he is online anyways. He despises X and views X as a rival or an obstacle and knows that X is actually very ignorant. He has a history of threatening the keys such as unown and marshsay and cannot be easily killed as he can just slip into his shadow dimension whenever he feels the need to. It's been theorized that the shadow dimension that Yenne resides at most of the time, gives Yenne a link to the real world as well, however that has yet to be proven.
It's also been said that Yenne has a "weapon of deep void" which he used to place roblox into a void world and preventing Ascension from happening in July, 2016 rather than August, 2017, however it doesn't really necessarily mean that he was helping RIFT as X was not released until later and without X, Vortex cannot win in Ascension. RIFT is still uncertain what is true and what isn't in that ordeal where the fake ending occurred.