What blocks the "pull" from Thorn Whip?
Thorn Whip: …and if the creature is Large or smaller, you pull the creature up to 10 feet closer to you.
As a specific example, the druid pulls a creature that is 15 feet away, but right in front of the target (and between the target and the druid) is another creature. Can the target be pulled through the other creature?
Does it matter if the other creature is an enemy or ally? Does the other creature have any choice in the matter?