One wonders what all the mediation Harry is undertaking in Little Things is for. The Law makes it clear he isn’t sleeping and has now fully equipped his personal armaments, and he is stymied on the Thomas and Justine situation, so I think he is doing something, something big, and something he hasn’t done before and which might impress even Eb.
I think he is moving the access point of the Castle from Leas Murder Garden in the Never Never to somewhere a bit safer, as a panic room for Maggie. The Winter Knights quarters in Arctis Tor, deep in Winter. I think having Toot and the Za Guard move in was to aid this, they are Winters Soldiers so both are now fortresses of Winter staffed by Winters warriors and both contain the personal quarters of the Winter Knight. Is so that is a feat we have only seen someone at Leas power level or above achieve. Mab almost certainly helped with Hades Vault.
If that works then if the Castle is under attack, Maggie and Mouse go to Arctis Tor under Mab’s protection as the child of her Vassal, and Harry is free to wreak havoc on the intruders.
I have posited that Arctis Tor also contains the access point for Demonreach in Mab’s Ice Garden, which the Gatekeeper and Mab used Harry might not realise this. When he does he can parkour along the corridors of Arctis Tor to Demonreach in a couple of minutes to get crystals or superweapons.
The other thing he is probably working on is how to teleport himself and the bad guys to the Lakeshore so he can summon Alfred. Water grounds magic so it might be a bit risky teleporting over a large body of water. That would explain why Demonreach is on an island. It strikes me that following The Law there is a nice Lake Shore residence whose owner has gone missing and won’t be missed, which would be ideal to set a circle up on.