I'm brainrotting over the thing we see in Mamere's world quests, where each Mélusine has a "token" aka a small object that serves as their "proof of life" and is probably their single most important possession ever, because like. There's not really any human equivalent. So Wriothesley wouldn't really understand how/what/why Sigewinne considers this thing as almost as valuable as her own life, he just knows that it's important to her.
So I think if something were to happen, like Meropide springing a leak somewhere near Sigewinne's quarters, it'd cause a lot of distress for her. Everyone gets evacuated, because no, it's not pure Primordial Seawater like from the sluice gate, but y'know, it's still rushing water and still dangerous. A lot of inmates get banged up in the panic of evacuating and the flood, and as badly as Sigewinne wants to leave and go back for her token, she can't ignore it when her patients are hurt. So she swallows it down and blocks it out and tries to just get to work and desperately hope she can find it in the wreckage later.
They do a headcount and everybody but their duke is accounted for; someone remarks they saw him running towards the source of the water. Sigewinne is equal parts relieved and worried, because if anyone could at least temporarily stop the leak it would be Wriothesley, but also he gets reckless sometimes, so she really hopes he's careful about it.
It takes a while, but some of the inmates start yelling over by the rails, and when Sigewinne tells them to move over, she sees that Wriothesley is trudging his way back up to them from the lower level. The inmates are all so proud and excitable! That's their duke!! Wriothesley looks up and sees them all hanging over the rails, and from here Sigewinne can see that he's completely soaked. Wriothesley's skin is all irritated red and fever-flushed from the diluted Primordial Seawater, and he's littered with bruises and scrapes from the current battering him against the walls and the floors and the pipes and all kinds of debris.
Wriothesley looks up, but he doesn't say anything at first, he just scans his eyes back and forth over the crowd. Until finally, he locks eyes with Sigewinne, and raises his arm up.
And in his hand is the bag that Sigewinne keeps her token in.
And the inmates, not realizing what he's holding, take his raised arm as a victorious fist in the air and they all cheer haha. But Wriothesley doesn't look anywhere else, doesn't smile for anyone but Sigewinne. ♡