Actually we are fighting in position 60N25E, because the southwest corner of the square is the point of reference, which is behind the tick. Small nitpick, irrelevant to the action.
Hits! (Rolled 19) The tick attaches itself amongst the penguin's feathers.
Critters with zero reach don't get AoO's against each other, so the tick's attack was a standard action. It can do the blood drain next round as a full round action or it can persuade the penguin to join the forces of LE right away as a free action. The penguin needs to make a DC 15 Will save to resist the tick. Otherwise the penguin is still hungry and will try to peck Super Tick out of its feathers.
No AoO...right...Opus never left a threatened square (the tick is obviously disoriented in a such a large open space).
So - let's go with the Free Action convincing thing, in the hope of avoiding a no DEX-to-AC peck.
At the Tick's bidding, Penguin-o Bull Rushes the scorpion. The Big Tick readies an action to attack the scorpion after the Penguin enters the scorpion's square.* (I'm hoping the penguin has a Speed of at least 10)