Galvatron thinks for a second, checking his own instincts; and then works out that there is an answer to that question, and he knows exactly what it is! "Because you didn't think I would!"

He's speaking out loud now, for Auspex's hearing as much as Scourge's. "You thought you didn't matter enough for me to come back for you, Scourge, hmm? Well, wrong!" He grins. "I'm sure Auspex has been assuring you that your former allies can learn to appreciate you again, but she's not a Decepticon, is she? What would she know?

"So! I thought my word might carry more weight with you than hers!"