I think part of freeing Thomas will involve Papa Wraith's death.
I don't think Thomas' next role is as KotC but as the next White King. The trick will be having Papa Wraith take the fall for the Svartalves assassination attempt and getting Thomas cured tied together in an impeccable story that also implies that Lara was the mover and shaker behind the scenes.
If Lara and Harry can make it seem that they've been allies for a longer time, then typical White Court paranoia will sew just enough doubt that Harry might be acting and is secretly a masterful deep schemer. Don't laugh,
Lara was half convinced of this at the end of Peace Talks and she has more inside information on Harry than 99% of the supernatural world. From the outside, you can make a case for Lara and Harry being a team since meeting on the movie set.
The timeline actually flows pretty well for a conspiracy theorist.
Harry and Lara meet on the movie shoot, She defies her father's orders to kill him and works with Harry to perform a palace coup.
It's Harry she calls upon to defeat the first real threat to her power in White Night. He doesn't leave with the rest of "his" allies but accompanies Lara back to the mansion.
Harry is called in to deal with the Skinwalker and the attempt to restart the war with the White Council in Turn Coat and she delays her departure until she can personally speak with him.
Harry is the person who makes all her introductions in Peace Talks.
And now, she engaged to Harry, the Winter Knight, just as the White Council kicks him out. His role as her spy in the White Council has reached it's end, now they will inveigle the Winter Court together.
The next step is to finally put away Papa Wraith and install their pawn/co-conspirator Thomas as the White King while building their powerbase.
Wizard of Chicago comes next. Harry and Lara spend the year before their marriage getting him in with the Chicago social scene. Operating a new magical organization will be a perfect cover for their secret activities. It won't fool the Accorded Nations but it'll do a fine job against mortal authorities coming in after Battle Ground. A big flashy target that does authentic good works will build up good PR at the least. Drop a few juicy secrets for the Men in Black to discover and they'll inevitably take the easier route and focus their attention there and away from the really important stuff. Pretty good improvisation to cover the completely world changing event Ethniu caused
The Immortals will know this is all nuttier than an explosion at the the Planter's packaging plant but for the majority of the Supernatural world
Looks like a master plan between the Queen White Court schemer and her young new Wizard lover.