Dead Man's Blood tag
John's glad to be back with his boys and wants the demon to die a painful death but it's like a clock is ticking, and he can't figure out why. He also desperately wants them both to have a normal life when this is over - that's something they both deserve after the hell they've lived through since Mary died. They deserve to be happy after everything they've been through.
If he dies killing this demon like he expects, then so be it. Maybe he'll finally be reunited with the love of his life and they can be at peace together.