If there had been anything Terrence could have done to help her hold on to that thought, he wasn't coming up with it fast enough. Maybe if he had Ella's talent, he could have helped that knowledge stick in Katie's mind, but his talent was in protecting his own mind, not putting anything into anyone else's. He'd helped the idea form in Katie's mind, but prevent her from forgetting it? That he couldn't do.
And it was gone. He knew it, he could see it as soon as it disappeared. The dull look in her eyes made him so angry he couldn't even speak, hadn't managed a single word except for her name in quite some time, and yet so much had happened.
He'd gotten close. He should have been taking heart from that, taking away the knowledge that it was possible to fight off the potion's effects. Maybe it would get easier with time, maybe now that the idea was there - even if it had been forced down to her subconscious - she'd find the way to fight it off on her own. Merlin, he hoped so.
But until then, he wasn't sure he could take it. All his anger at having been under the potion himself was resurfacing, but he had to get that under control or he'd set her flat on fire. Brilliant, T. Give her the worst news possible, then burn her house down. No. He wasn't going to let himself get out of control. He'd done all he could do, except for that.
Well, and he could stay, if she wanted him here. He shifted closer, careful not to disturb Quaffle, and curled a tight arm around her shoulders. "Kick me out whenever you want to," he said, keeping his voice soft with an enormous amount of willpower. "Can I get you anything?"