A lamp flickered on. It was Hermione Granger, wearing a pink bathrobe and a frown.
"You!" said Ron furiously. "Go back to bed!"
"I almost told your brother," Hermione snapped, "Percy –– he's a prefect, he'd put a stop to this."
–– Harry Potter and the Sorcerer's Stone
The highlighted part, I would say, has different Reference Times: telling’s RT is the past; put’s RT is after the Speech Time. If this is true, I can imagine this sentence: ‘If I told him what you’re going to do, he’d put a stop to this’. Is it right?