Okay so in shipping culture, most ship names are both characters. Generally for these ship names, the character that would be the “top” in the relationship goes first, followed by the “bottom” in the relationship.
So for Dimentio x Mr. L, I would use Limentio, suggesting that Mr. L is the top and Dimentio is the bottom.
Now with the Top / Bottom context there is also Dominant / Submissive context.
Am I saying that Mr. L is dominant? Absolutely not. That is a submissive top right there. He still has the shyness of Luigi when him and Dimentio are going at it. Dimentio on the other hand? Yeah that’s a dominant bottom. But it’s like a soft dominant, nothing violent and degrading. He’ll hold onto Mr. L’s hips and guide him.
It is almost midnight for me when writing this. Do not ask me what I was doing before writing this.