One of the main requirements of a effective Warden is his or her will. That was evident when Harry bound the Titan and sent her packing via Alfred. He almost broke and would of if it hadn't been for the foresight of Molly, keeping her family safe and excluding Mouse in the vision as a message to Harry that Maggie would be killed over Mouse's dead body, and it wasn't there. Also important, no critical to his success was the vision of his daughter hugging him and his dog by his side..
Foresight and hindsight, he realised Mouse was not shown, and if there is one universal constant Mouse IS A GOOD BOY.
Harry thought when snaring Demonreach that he was making a lesser sanctum, this would allow him and only him to tap the ambient magic of the sanctum giving him an advantage over other wizards. A lesser version of the magic high in Battleground but only for Harry. Instead he snagged a genius loci, a powerful one, her gets the ambient magic, plus intellectus, plus control over the island and its defences plus Alfred. Warden isn’t a Mantle, it’s a marriage (sorry Lara, Harry is already spoken for) I suspect Alfred is programmed to turn on a Warden who seeks to release the inmates unless those inmates are being used to entrap others. And Demonreach would know, due to the mental connection. I think Alfred thinks of Harry in exactly the same way that The Redcap thinks of Molly. In PT Alfred sneaked up on Harry without the intellectus informing him, that the security protocol. I suspect Alfred divorced Kemmler and probably tried to kill him.
Two wizards had been Warden after Kemmler, either Alfred divorced them, or they divorced Alfred. Maggie Senior was being groomed by Eb to take over as Blackstaff (lovely), so not her perhaps. Maybe Petrovich or La Fortier divorced Alfred as it became inconvenient to be Warden and a Senior Council member, to allow someone else to take up the duty which then killed them.
