Plot
Think about it. Billy's not the problem. The problem is Wanda Maximoff. She's the one who lost her mind. She's the one who made mutants an endangered species. She's the one who murdered my dad. And why did she do all that? Because she thought she'd lost her kid. So if we can show her that her sons are alive and well, she can undo it all. All of it. And can reverse the spell, give the mutants back their powers...and she can bring my dad back to life.