Not what I had in mind, though I could certainly use this

As Ferb embraces the boys tender and loving hug
phineas looks at the boy and his brother with the intent to murder
When he leaves and says Enjoy your last 24 hours
As he creeps in ferbs room that night and stabs him many many times
Then phineas call the police to turn himself in.

ferb must protect the child from Phineas, who is too far gone in his murderous rage.