1. Handing over the Book of Kemmler to Mavra. She was blackmailing him, but was protecting a friend from her career getting ruined worth handing over a book like that to a monster? I don't think so, and I imagine it's going to come up again.
Already did, the book allowed her to cozy up to Drakul big time and recruit some Wardens into her service. Further cemented what ever Carlos thinks he suspects Harry is up to, because he holds Harry responsible. On the other hand, blackmail is never as simple as it appears to be, otherwise it wouldn't be such an effective dirty weapon
2. Staking claim to Demon Reach. This was a really big move, and it seems to have worked out well for him. That being said, Jim said "He's going to wish he never stepped foot on that Island". So I imagine it was a bad move.
Bet he already wishes that, on one hand he was able to save Thomas's life by imprisoning him there. However if he may never be able to ever let him out again. It appears up to this point anyway that the only sentences Alfred hands down are life sentences. I think Harry is going to find that hard to live with.
3. Splitting up Bob. Seemed like a good idea, but I think Evil Bob is out there, allied with who knows who. He had access to horrible knowledge. Can't imagine that will end well.
That was a result, not a conscious choice I think.. Harry was more like Pandora, he needed information about a time in Bob's life when he served the ultimate evil wizard. Bob begged him
not to do it if I remember correctly but couldn't or wouldn't explain why. Once called up, Evil Bob nearly killed Harry, Evil Bob was suppressed once more, but this time was able to splinter off. Yeah,
bad news, but like in the myth Pandora also released "Hope" when she released all the trouble on the earth, Good Bob was also returned to serve.
4. Killing the entire Red Court. Some of that may be becoming apparent already with the Fomor. I'm wondering if Harry will realize he had another option, and the one he chose was the wrong one. As a wizard I'm wondering if he could have worked out a spell, and used that source of power for something else, rather than sacrifice Susan and wipe out out the Red's.
I don't think Harry had any good options in this case because the spell that he reversed that ended in the demise of the Red Court would have ended in his own demise and that of his child and Eb and most likely Thomas. The only possible one I can think of is if he had found a way to kill the Red King before he killed little Maggie.. It looked like at that point anyway that that wasn't going to happen, even though Harry was backed by some real heavy weights.
Just some off the top of my head. Can you think of some critical decisions he made that may have appeared right but will return to haunt him later?
His night of unprotected sex with Susan that resulted in the birth of little Maggie. True, he got a beautiful daughter but see regret number 4, for the consequence of that little act.