I mean the new one, in the 0.7.5 cover, it kinda looks like a lion ig, not really good with names, so sorry if it confuses you.
Oh, my bad! Then I hope you're talking about Null, who is a royal ludroth, not a lion.
After talking to Mitryll and getting more travel sigils, head back into Rett's cave. Pass through the cavern hallway, then when you are near the room with Rett's hoard, you should get a brand new event, one that urges you to enter the treasure room. Enter the treasure room and jump into the hoard of stuffed animals! You should be able to find Null from there.