Petaal turns into a ball python and wraps her coils firmly around Kas's torso; he hugs himself and leans his head against hers and shivers happily.
All of this takes about three hours. The Starks and Bell are now protected - not perfectly, but considerably - against many forms of natural disaster, disease, injury and drugging; anyone trying to invade their rooms will get a nasty surprise; they will wake up if danger approaches while they sleep; and in the event that one of them dies anyway, the other two will know it at once.
Kas and Petaal are absent for the majority of the spellcasting after that first one.
Isabella can guess, too, but if the Starks don't mind a guest slipping off, she has no reason to object.
When she's sure she's exhausted the likely-useful spells that Isabella can cast here and now, she hugs her, hard, and asks Tony if he can get a Milliways door so Isabella and Kas can go home. "If I were her I wouldn't want to stick around longer than necessary," she sighs.
She hugs Shell Bell. "I'll see you in the Belltower. We can leave notes even if we don't run into each other again in person anytime soon."
"Of course," says Shell Bell, hugging back hard. "Thank you so much for everything."
She squeezes, hard, and then she lets go.
"Kas!" she calls. "Petaal! Let's not leave Tony holding the door forever!"
Kas and Petaal appear in short order, Petaal draped across his shoulders as a linsang, Kas fully clothed but looking like he only just got that way.
Out they go, with a final wave to their hosts.
"Oh, give me an hour and I'll have something ready to try," says Isabella, wasting no time in opening the door again to her room as soon as it's shut to Panem. Everything is as she left it; good. She puts her cloud-pine down, picks her notebook up, and gets to work.