"I know," Severus answered with a shrug. "But it's only a temporary measure, until you feel that you can protect yourself on you own. And now you've told me, haven't you? So you don't have to avoid Marlene any longer, if you don't want to."
He nodded thoughtfully when she said Lupin had been helping her with disarming. That was a good, basic spell, and it ought to help her head off trouble before it started in most instances. "I'll help you with internal defenses," he said then, nodded again, this time decisively. "For when dueling fails. So that you can resist the Imperius Curse, if it's ever cast on you again."