Do we know whether Lara is able to feed off of Harry? She surely could BEFORE he became the Winter Knight...
We don't know if Harry's relationship with Murphy would have protected him, or if it hadn't gotten deep enough / serious enough.
I like to think it would have -- I ship Murphy with Harry, tho I think Molly was a better fit for the long term, just because they both have centuries of lifespan (unlike vanilla-mortal Murphy (but who knows what Einerjar-Murphy (or whatever) will have)).
But I'm very dubious that Harry *ever* got that protection via Murphy... I need to go back to
Peace Talks, and re-read the scene where Harry spars with Lara in her home dojo: IIRC, that wound up with some unarmed/grappling, and
that would get skin-contact, and I don't recall Lara getting burned?
Do we know whether Lara is able to feed off of Harry? ... can Harry's mantle counter the efforts of Lara's demon?
I am pretty sure there is WoJ specifically saying that the WK mantle's sexual urges & the Whamp-whammy sex thing are additive with each other. No immunity for the WK.
I expect Lara would die (tho it'd be a close thing): she seems a bit smitten with Harry (in her own predatory way) and I don't think she could resist trying the classic whampire "pacify with pleasure" schtick.
In self-defense, Harry would do the WK-Mantle "sex
with violence" thing, fueling both his own magic and the WK-mantle with Whampire sex-mojo.
Lara would do well to remember who kept their self control, there in the Raith Deeps and the brief "cannonball run" over the estate. We
know Harry can fuel his magic with whampire sex-mojo, and he's only been honing his will colder and harder since then.