I think the "No catch" option has merit - it could well be better that we minimise the notion where possible that she will forge new chains by throwing her lot with us, so that more mutually trusting relationship is formed longer term, but on the other hand, it would be both arguably a little deceitful to not admit we have hopes of working together against the Denarians, and trying to hard-sell "no strings attached" would probably (at least at this stage) raise more red flags than calm concerns for Lash, considering her current scepticism and cynicism about, if not the earnest purity of our motives (which I'm sure remains a lingering doubt in the back of her mind), then certainty the fallibility and corruptibility of mortal mind, motives and souls, even those (or perhaps especially those) as ascended as our own.
Therefore, at least for the moment, I think Yog's modification of Artemis1992's proposal is the best compromise for now, assuming I'm interpreting it right - a compromise or middle approach between "Make common cause against common foes like the Denarians" and "No Catch", where we give an open-ended offer for the most tentative collaborative approach, but make clear that her promised body is in no way conditional to whatever she decides in a gesture of good-faith and respect of her personhood.
[X] Make common cause against common foes like the Denarians
[X] No Catch
-[X] Stunt: I think we have a common interest in opposing the Denarians, but we can talk about that when you have your body. The deal is freedom for you and Harry and I'll stick to it. If you ever stab me in the back, it will be for your own reasons, not because I tried to shackle you in the moment of your birth.