It wasn't that he hadn't thought about it. Damon had, in fact, considered what would happen if Ric's identity were exposed.
If it had happened in the past, he would have feared that Ric could be taken from him by force. However, things were different now. If Ric's identity was exposed, Damon would probably have to sit through a few long meetings with House Ravenscroft.
After all, Ric's own father was the one who had traded the boy to him. There was also the issue of Ric having lived in the Tomb, but Damon was confident he could keep that secret for a few years.
Furthermore, only the weak feared those in power.
Damon was no longer weak.
He possessed enough military power to face the entire Empire. He could also crash the Empire's economy within a matter of days if he truly wanted to. It wasn't an exaggeration to say he was the wealthiest person in the Empire, and if everything devolved into senseless violence, he would still win.
