Zacharias & EVERYONE
When Ernie spoke, Jasper's attention left Zacharias's - long enough for him to draw his wand. Whatever stirrings of sympathy Ernie might have caused in Jasper for Zacharias was squashed completely when that explosive spell was cast.
Jasper jumped in surprise along with everyone else, Zacharias's last remark ringing in his ears. He watched Zacharias go for the door, but didn't follow, instead calling after him, "Once a coward, always a coward, eh, Smith? You get treated exactly how you deserve." And Jasper was done with him. He had more important things to worry about - like seeing if Justin and Bianca were okay.
As he started back to wear he'd left Bianca, Jasper cast Ernie a look. "Stop making excuses for him. He's the last person who deserves it."