Snape as Headmaster

[potioncat]

No: HPFGUIDX 189223


. 
>   Bart:
> Of course, reports of his giving rebel students detentions with Hagrid 
> gives us a clue.
> 

Potioncat:
Less obvious, I think, is Snape's comment to McGonagall about it being her night to patrol the halls. Makes me think that HM Snape assigned Heads of House to patrol the halls at night to catch wayfaring students. If they caught any they would of course report them to the Carrows. Big if, you know?