now X says it isn't Evan's train. He claims it was a purchase from my stepdad and that he left it to X which isn't true at all.
My best guess is that the train has some resale value and your ex is aware of that (or thinks that, even if it's not true) and is willing to throw son under the bus to hold onto it for the money. What a weenie.
Also, which is it? Did he buy it from stepdad or was it willed to him? Can't be both now, can it?
