That looks like Ser Criston in the background, while Alicent and Otto stand with the older versions of Alicent's children, Aegon, Aemond, and Helaena. ?
Things are not looking good for Viserys. .
Things are not looking good for the Sea Snake, then, either. .
He's clearly concerned about the succession if Corlys dies, now that both of Corlys's children are dead.
Vaemond emphasized in Episode 7 the importance of keeping their bloodline pure, a clear reference to Rhaenyra's children being bastards and not Velyarons.