"My thoughts exactly," Abigail agrees.

She has a couple questions also, about Abigail's experiences with Lab Five... 

Gideon catches them at the end of this conversation. 

"Speaking of," she says to Phaedelia after, "Ellyn and I want to head back down to the labs this morning, try our hand at Lab Five."

"It has been a little bit... I'll have to double check with Phoe and Babs, but we should be up for that - I can also check if the Sixth want to tag along."

"Thanks."

"No problem."

She passes on the invitation to Palamedes and Angerona, before finding her twin and cavalier (and letting them shove food at her).

It's a party at Lab 5, and the whole study group's invited.

The trick to this one, according to Abigail, is dipping into the River, the extradimensional space between this universe and the hereafter, where swim the ghosts of the dead. There is a passcode to be found, etched into the bank of the portion of the River "nearest" to the lab space.

So it's a trick of anchoring the soul - knowing what they do now about Lyctorhood, this was probably the key to pinning the cavalier's soul in place...

It's a trick of Resurrection, too.

Or of actual travel of some kind - the system of using steles to travel between obelisks does involve (very shallow) movement through the River, without anyone in particular's soul being anchored. 

Stele travel seems like a red herring here. A side effect, not what's being tested.

Might be what they derived obelisks from, though.

Still gets them back to 'anchoring' - whether her soul enters the River with or without her body wrapped around it, she'll still need a way to avoid falling too deep, and then a way back. 

Palamedes is thinking about maybe a modified spirit ward? At least as a guide to help keep hold of a soul?

There's also what Gideon and Ellyn have learned from the prior labs - they could maybe (she gets out pencil and flimsy and starts doing math plus taking notes) - they could anchor Gideon's soul to Ellyn's, Transference looped back in on itself - they've already figured out how to let Ellyn do necromancy through Gideon, and the thanergy/ thalergy loop from Lab Three and then the controlled excitation of thanergy from Lab Four would produce enough power for an active connection, plus allow Ellyn to maintain wards on Gideon - like in Lab Three, except protecting her from the River instead of from fire - and then she could alter any theorems on the fly - 

That kind of loop would also provide a thalergetic pressure actively pulling the cavalier's soul back to her body - the necromancer would need to very carefully balance the thanergetic and thalergetic blooms so the cavalier proceeds slowly and controlledly into the River, though return should be relatively easy as shifting the balance to thalergetic generation would immediately eject the soul from the River - and thanergy-thalergy conversion is useful for healing, of course, so it'd also prevent the cavalier's body from suffering damage in the absence of the soul - 

Yeah, exactly - 

Wow. Nerds.

Hot nerds, excuse you. 

All right, Gideon has her there.

What are Ellyn's thoughts on this, by the way? 

That they are indeed hot nerds.

Looping is a solid strategy, and Ellyn is confident she can keep hold of Gideon's soul.

"I trust you, my venerable void princess." Then the question is details, including how to tether Gideon and how exactly to go about separating her soul from her body...

The quickest way is obviously to kill her. Just a little bit.

Shiver! (Her pupils dilate a little - she is trying SO HARD to be serious about this, BUT.)

Ellyn's choice how, of course. Gideon has way too many ideas to narrow them down.