adw064 Ghost Rider

A opposing character is adjacent to the edge of the map, Ghost Rider's player wants to activate VENGEANCE WILL NOT BE DENIED to attack the opposing character but Ghost Rider cannot move past the opposing character square because it's the edge of the map. Can Ghost Rider move into the opposing character square than move backwards towards where he started his move action (in the same straight line of square movement of course).

No. A direct path means a straight line of movement in one direction.

Looks like Vengeance CAN be denied.

From WIN errata and clarifications, under Movement:

[C]A game effect that refers to movement along a direct path is the same as if referring to movement along a direct line.

Is there somewhere else it clarifies "one direction"*, because I've always played pieces like this as described in the op, unless the power specifically said "one direction". Especially using things such as Juggernaut, to destroy several squares of blocking on either side.

*insert mass manufactured pop boy band puns here

Yes, the rulebook, pg. 9-

Therefore, Ghost Rider, Black Knight, Valkyrie, and other characters are all subject to moving like a boy band: One Direction.

What if Ghost Rider were to end its movement is a square occupied by opposing characters? Could Ghost Rider's power take effect because he moved through their squares? They will be placed afterwards anyways. Or, will GR move, attack, finish, then opposing place? How does it work?

VENGEANCE WILL NOT BE DENIED: Ghost Rider can use Sidestep. Give Ghost Rider a power action to move up to his speed value in a direct path. After actions resolve, choose: 3 damage or 2 penetrating damage, then make a close attack targeting all characters he moved through. Hit characters are dealt the chosen damage instead of normal damage and placed into a square that Ghost Rider did not move through adjacent to their current square.

He cannot end his movement in a square occupied by an opposing character as that is prevented by the Golden Rule of Occupancy.

The order is: he moves, the action ends and he gets an action token, make the attack, place the characters.

Thank you.