[X] Plan Don't Do Everything Alone
-[X] Tell him that you tried to help him as much as you could and what was said between Otto, Corlys and yourself, including noting that Corlys cast doubt on the value of House Targaryens word.
-[X] Lay out that you quietly looked for other possible matches for him to avoid the Sea Snakes offer without instead having half the realm try to force their daughters on him.
-[X] Lastly close that you have fears that Otto might try to present Alicent as an alternative, though you can't name where that dread comes from.
-[X] You did all this out of a desire for him to be happy and the house strong, hoping that there will be no more fighting about succession and that he would have time to grieve and heal.
[X] Plan Don't Do Everything Alone - Simple Version
-[X] Plainly tell your father about the discussions you had with Otto and Corlys, and the other possible matches you found.
-[X] Also discuss the persistent fears he might marry Alicent you keep having.
[X] Plan: Be Our Father's Support
-[X] List the three matches we have as alternatives to Laena: Victaria Tyrell, Deria Martell, and Johanna Westerling. Discuss the relative benefits of each. If some levity is needed, jokingly offer to fly to Volantis and see if you can find some of his wayward cousins to bring back. Mostly however, focus on being a support for your father, so that he knows he is not alone in this decision, and that you will fight for him if need be.
[X] Plan: The Spicy Option
-[X] A Dornish match would be beneficial for several reasons. One, the heirs would be very incapable of acting as usurpers. Like it or not, the ruling of having a daughter as heir is tenouous, and an ambitious family could use Viserys' son as a rallying point. Two, Viserys would go down in the history books as the King who both conquered the Step-Stones and the one who began to bring the last Kingdom into Westeros. It would also silence those who may see this as Cotlys Velaryon's war. And three...more personally... the wisdom of the Dornish and their female rulers might be availed to his struggling daughter.
-[X] If the marriage is paid in blood on the Stepstones, fighting with the rest of Westeros, it will silence at least some of the dissatisfied whispers. And if unrest grows too much then I can be the one who brings stability with marriage next time. You don't deserve to be the only one suffering father.
-[X] PLEASE, don't marry Alicent. She's my best friend. And I know you and Otto are friends, but you know how ambitious he is. He can be almost as bad as Corlys. If his grandson had the chance to sit on the throne over me it might get...messy.