verse for Viserys:

Viserys of the House Targaryen, the Third of his Name, King of the Andals, the Rhoynar, and the First Men, King of Yunkai. Lord of the Seven Kingdoms and Protector of the Realm, The Unscathed and The Breaker of Chains.

He survives the golden crown. He’s still cowardly and prone to outburts of rage but after seeing Dany come out from the pyre and with three dragons no less, he too finds himself bowing to her.

If only for a brief moment in time. He knows Daenerys is Khalessi of what remains of Khal Drogo’s people but he still sees himself as the rightful King of Westeros. He goes to the Undying House with them, bonds with the White Dragon which he names after himself (this could change….maybe be named Rhaellion after Vis and Dany’s mother?)

As Dany conquers Yunkai, Astapor and Mereen, freeing the slaves and destroying the slave culture ect. Viserys stays in Yunkai with a few people that stay behind with him and finds himself a person much like
Missandei. He takes a few thousand Unsullied with him and rules Yunaki as it’s king. He hears about Daenery’s disappearance and caught between keeping Yunkai and Meereen safe from any Master’s who would want to reclaim what was taken from them, and going to find Dany. He takes his dragon and leaves after a few days, making sure both cities aren’t in ruin and finds Daenerys with more Dothraki at her command.

He sails back to Westeros with ships and armies at his back and goes home. No longer the Begger King, but the Rightful King.

Honestly can see things playing out the same from season 6 onwards. He and Dany could joint rule, and gives Dany the tittle of Lady of Dragonstone (and his heir/princess if they do not joint rule)