Final answer:
The question references a character who betrays his father to side with Arthur as king, a theme common in tales of royal succession and medieval literature, but without a specific text, identifying the character is challenging.
Step-by-step explanation:
The question asks about a character who sides against his father to accept Arthur as king. This aligns with themes often found in literature, particularly within the context of medieval stories or those involving kingship and succession. The excerpts provided, while not directly related to Arthurian legend, evoke themes of power struggles, betrayal, and the complexities of royal succession. However, without a direct reference to Arthur or a connection to a specific text, it is difficult to pinpoint which character the question refers to. Nonetheless, if we assume the context is related to Arthurian tales, characters such as Mordred or even Lancelot at different points could be seen as siding with or against familial ties due to their allegiance to Arthur. It's important for students to closely examine the literature they are studying to identify characters and their loyalties.