Altruism isn't something that Druitt is much inclined to. But he is an old hand at violence, and for all that having to deal with rampaging plant life is a little outside the scope of the usual, for him he figures it's best to take what he can get. Besides, the pair of swords he's brought back from the Arena will be just as good for this as anything else, and fewer people are likely to complain about him working out any latent aggression on a bit of over-active vegetation than anything else.

(He might not be against the idea of sparring, but it's not really the same, in the long run.)

He happens across Fortescue just as she sets herself on fire, and for all that he's known more than a few people with unusual abilities (himself included) that isn't one that he can say he's seen much, before. There are elementals, yes, but those are really more to do with the embodiment of an element as opposed to someone who can simply bend it to their will, as seems to be the case here.

"Impressive."