If you could advise Viserys I immediately after Aemma's death (assuming you have no knowledge of future events), would you tell him to remarry? Why or why not?
I would tell him the absolute and unvarnished truth. Royal marriages are meant to create dynastic succession so marrying another woman will create a branch family who would anticipate becoming part of the royal line, especially if you have a son. So only do that if you don't want Rhaenyra to ascend after you.
This requires no actual foreknowledge of the Dance of the Dragons - Maegor is proof enough of the danger a branch member would provide and Jaehaerys's ascension over Aerea provides justification for male-preference primogentiure. You also have Daemon the Rogue Prince waiting in the wings, and he is a chaotic monkey wrench to throw into the mix because he also wants his own crown. You're already going to have problems with him, so unless you want to make things even harder for Rhaenyra's inheritance, don't do it.
Thanks for the question, Anon.
SomethingLikeALawyer, Hand of the King
I would also add, for the love of God, stack the Small Council with Rhaenyra loyalists.
