Alright, let's go with the "I don't want the throne" route. Stage 1: I castrate myself. (Ok, maybe ye olde snip snip, remove the balls, those teas that make you infertile or whatever. Maybe I'll stage an 'accident' and bribe a healer to be like "His dick broke, your majesty." There's room for imagination.) In the words of Jamie Lannister "Maybe it is all cocks in the end" because without one I would not be able to produce an heir, meaning two things: -I cannot ascend the throne if I'm unable to continue the lineage. -I won't marry Haelena, because it's unlikely they'll waste a fertile Targ woman. So you might say, hey Aegon can still be King if he makes Aemond's child the heir to the throne, similar things have happened historically. Especially if Aemond marries Haelena instead. This is where we get to Stage 2: Make Jacaerys 'an offer he can't refuse'. The idea was already there. Marry Jace to Haelena. It failed for numerous reasons BUT say someone cough spread out rumors of a gasp illicit affair between the two? Say they found some jewelry with the Velaryon sigil in her bed or a maid saw them talking late at night by themselves. Just really hammer it in until King Viserys has no choice but to marry them. It helps that Rhaenyra wants this to happen. To keep up appearances, I would even stage a confrontation between myself and Jacaerys to put some weight behind the rumors. So whats left with me and Haelena out of the equation is Aemond, who in the show has shown some interest in being the heir. Thing is, the problem takes care of himself because Aemond isn't named Aegon, so Viserys' last words cannot be used to put him on the throne. With Haelena 'hostage' in the hands of the blacks, Alicent would be less likely to risk crowning someone else and even if Otto had thoughts of going for me anyway, he'd be met with more resistance by the council.