Lending strength in Chrestomanci
So I just noticed this subtle parallel in incident in the Pinhoe Egg with Gwendolen's use and abuse of Cat in Charmed Life.
Gwendolen has been stealing Cat's magic from well before he was old enough to notice it or consent to it, and she gets angry with him when he takes back control over it. She feels she's owed it, she only cared about him for how useful he is. This also suggests that it's a relatively easy piece of magic to do (she's said to be a fairly average witch in terms of raw power), and that conscience/law are what hold most people back from doing it (though Cat being an infant at the time probably helps. It's also possible that Gwendolen herself, being a small child, didn't really realise what she was doing until later on).
Contrast this to the egg-hatching scene in PE, where Millie helps the egg hatch. Irene, Cat and Millie lend the egg their strength; Irene doesn't know how, so Cat 'does it for her'. The 'strength' required by the egg is physical, but it does seem that they're lending it magical strength and it's certainly done by magic. Again, this is the taking of someone's strength/power by someone else, but the difference is that Irene very clearly wants to help and has consented to lending her strength (by placing her hands on the egg), so Cat is only facilitating the process, and the power is ultimately being used for good, to save the griffin's life.
I'm sure there are other instances of strength-lending in the novels, but the ones I can remember involve a willing and deliberate lending of your own strength to someone else.
(Pardon any weird grammar or phrasing, I am very sleep deprived)
