My dear, treacherous mother,” he breathed. “What have you done?

Your enemy will always plan to destroy you in any way possible thus take care of your friends, he may use them.

I feel duped. But more importantly, I feel that you betrayed millions of readers.

What was there to be gained by fighting the most evil wizard who has ever existed?" said Black, with a terrible fury in his face. "Only innocent lives, Peter!"
"You don't understand!" whined Pettigrew. "He would have killed me, Sirius!"
"THEN YOU SHOULD HAVE DIED!" roared Black. "DIED RATHER THAN BETRAY YOUR FRIENDS, AS WE WOULD HAVE DONE FOR YOU!

It's only possible to betray where loyalty is due

There’s more.”

“Of course there is,” Brishen said flatly. It had started badly; it turned worse and hinted at becoming ruinous.