I believe  Grace is Red John
Her sister is Harker Rosalind ( both red haired, similar age and looks). And NOT blind. We are told Red John is male because of her. false info to hide her true identity and would explain a lot.

I believe Tyger Tyger is like a beehive. Queen Bee at the centre of the hive and organisation. the ultimate betrayal for Patrick. She' s been watching him from the beginning.

Rigsby is either stupid or part of Tyger Tyger.