I'm gonna ramble about LiyuConberma's Cosium AU for a second. Cool? Cool.
So, one thing that absolutely fascinates me is trying to figure out what the Triple S Trio's middle names are. We know middle names exist in this universe. Mortesen's was Windfred and Kaze's is Negolas. Negolas is the name of Kaze's grandfather, Mortesen's dad, so I think we might be able to safely assume that Windfred was Mortesen's grandfather as well.
So if we stick with this pattern of giving your child your parent's name as their middle name, I have a theory for what middle names Sonic, Shadow, and Silver has. Shadow, since he's the oldest, has the middle name of Mortesen. I think it really fits, especially since they have main color scheme. We'll skip Sonic for a second, and go to Silver. Since Silver is set to inherit the throne of Atlantis, I think it would make sense for him to have the middle name of Sapphire's father, Poseidon. Also, Silver looks the most like that side of the family, so it's only natural that his middle name would come from there as well.
Finally, let's talk about Sonic. This one might be a bit weird, but I think his middle name is Karok. Let me explain. Not only would this keep with the pattern, since Athena took on the role of Karok for a time, but it's also a bit symbolic with how Kaze and Sapphire's love story went. (Kaze was also Karok for a time and used that identity to rescue Sapphire from Rakar towards the end of Tale of Origin.)
So yeah, to review, I think the middle names are Shadow Mortesen, Sonic Karok, and Silver Poseidon.
(REMEMBER, THIS ISN'T CANON, THIS IS JUST MY THEOY.)
Go check out LiyuConberma and the Cosium AU. It's really really good!