I just started playing Call of Cthulhu, and decided to pick up the 7th Edition. When creating my character I got confused about the sanity numbers. Theres a max (99-Cthulhu Mythos), start (POW) and current. My question is: can the current sanity go over the start sanity? And if so, does anything change in the character?
Yes, the current sanity can go over the start sanity (equal to your POW for a new character) if you manage to gain sanity (at the end of a successful adventure for example) while not having lost too much during the investigation.
Nothing really changes for the character, it's just less likely to go insane (for the time being that is, we all know where it's going to end :) )
Note that while it's technically possible, it's not something that is supposed to happen (slipping slowly towards madness is part of the fun in CoC).
But the current sanity can never go over the max sanity (determined by your Cthulhu Mythos rating).