They were barely moving, they weren't even trying to run. Perhaps they underestimated, but it didn't really matter. If they stayed put, it would be easy to get a hit in. Its venom would incapacitate them (or at least one of the two--there was no guarantee that it could get both), and then they would have no hope of getting away...

One was injured now, attacked by its own kind. That could make matters a good deal simpler, and the scorpion knew for certain which patient it was going to attempt to attack first. Always aim for the weak.

Perhaps it wasn't big, but it was much bigger than it was supposed to be--and its stinger was more than large enough.

It was closing in, near enough that it would be visible.