Hilderic was the grandson of Generic, who founded the Vandal kingdom in Africa. He also descended from Roman emperor Valentinian the third, thru his mother Licinia Eudoxia. Like his mother Hilderic favored Catholic Christianity(
https://en.wikipedia.org/wiki/Catholicity), something that the still mostly Arian Christian nobillity frowned upon. Hilderic was also friendly with the Eastern Roman emperor Justinian the Great.
Contemporary historian Bodo writes that Gelimer attempted along with his supporters to perform a coup. According to Bodo, this conspiracy was foiled and Gelimer and his supporters fleed Carthage after fighting the troops that were sent to arrest them. Hilderic then called for the conversion of all christians to the nicene creed.
The rebelling nobillity controlled much of the countryside, while loyalists controlled the area around Carthage aswell as many of the coastal cities. Initially the Arian nobillity had much sucess and eventually dominated much of the Vandal kingdom. This position weakened due to Mauri raids and a Loyalist counter-offensive supported by the Eastern Roman Empire. The support given by the Eastern Roman Empire was limited due to the Gothic war it was fighting in Italy.
With the unabillity of both the Loyalists and the True League(as the rebells called themselves) to achieve victory(Even though the True league still had a military edge over the Loyalists), combined with the precarious situation of the Vandal nobillities social standing(especially in the area controlled by the True League) made both parties open to negotiation. Outside Tunis the treaty of Ad Decimum was signed by Hilderic and the True League.
The treaty of Ad Decimum forced the king to share power with the nobillity. Intoduced new laws of succesion regarding kingship. Now the son of the previous king, or his closest male line descendant was to inherit. Guaranteed the property, rights and priveliges of the nobillity. The treaty also guaranteed all christians religious freedom.
Did i add to much text for a DBWI?