We're not killing Mareinette, lol. This is the Name of Heart, who stronger people than us spent eras trying to kill and failing. We've got a handful of turns, there's no way we're fitting in what would be necessary to have a chance of success.
We've got three options:
1. Befriend her. This gets us a very potent Name for All In, saves us further costs of rebinding, and can also secure Grail Level 5. It costs the actions of building a prison, acquiring a prisoner, and of course the moral dilemma.
2. We don't befriend her, and keep rebinding her. This gets us her actions for the remaining turns. It costs us a decent amount in 3 turns, and quite a bit in 6. It also does leave a Monster who can drop her bindings at our back when we go for All In.
3. We don't befriend her and don't rebind her. This gets us nothing, but maybe she's further from our estate/up to other things when we go for All In. This costs us leaving her free, which probably makes a mess that's the Lunar Bureau's problem. And our problem. Bad idea.
I don't think there's some sort of partial friendship. We know what we need to do to befriend her, other than that it's all just wishes in the wind where we're
actively choosing not to do that.
which sounds overly petty and punishing for Bird
This is a horror quest. This is a quest where we are grappling with forces stronger than ourselves, with all that entails.
There is a Monster we have summoned to the Wake, who
explicitly can break her bindings at any time. Who maintains the relationship because she is interested in us. Bird has no qualms about letting our choices, and sign-posted warnings, cause dire consequences.
If we're leaving her behind, I think it's reasonable to imagine she would leave us behind as well. An option she has. Biedde will be there too, so I don't think she'll run totally amok in the estate, but she can definitely get up to lots of bad things!