Normal
I would definitely be prepared to be asked about your mitigating circumstances and how they impacted you, but I feel being 'grilled' about them may be inappropriate for law firms to do, especially if your circumstances are sensitive in nature. Having mitigating circumstances doesn't mean you've done anything wrong, so be honest and transparent and explain why these circumstances impacted you and your grades clearly and how you've been able to recover from them, if at all applicable.