The way to do this is with one event that pretends it's the vehicle, so you can run some extra commands before putting the player on the real vehicle, coupled with a second parallel process event that monitors for the player leaving the vehicle, which can then run some extra commands when that happens. Come to think of it, you could probably have a single event with two pages.
First, put the real vehicle (dragon with rider sprite) onto a map that the player will never visit.
Next, create an event on whatever map will have the dragon, and this will be the "bogus" vehicle.
Page 1 looks like the dragon without rider. Trigger action button. THROUGH ON. Event commands:
- Gather Followers
- Make the player transparent (now, if this ends up making the vehicle itself transparent at the end, go with a Change Player Sprites to None for all characters instead)
- Set Vehicle Location - change the real vehicle's location to the same map, X and Y as the current event - probably use variables to do this, if you're going to allow the player to land anywhere and use the vehicle again afterwards
- Get On Vehicle
- Turn on Self Switch A
Page 2 is set to parallel process and has no sprite. Event commands:
- Wait 1 Frame
- If Vehicle (Dragon) is being ridden
- ... Get Off Vehicle
- ... Set Event Location (move the event to the vehicle's new location - probably have to use variables again)
- ... Set Vehicle Location - put the vehicle back on its original map where the player will never visit
- ... Turn off player transparency
- ... Turn off Self Switch A
So what you have is an event that looks like a dragon. When you walk onto it, followers are gathered, the player mounts the dragon (this is the combination of changing the player visibility/sprites, moving the vehicle, entering the vehicle and changing the active event page), and gains control of the vehicle. When the exit the vehicle, the player dismounts (again the combination of moving the event to the player's location, making it visible, exiting the vehicle, hiding it, and making the player visible again).
You may have to play around with the sequencing a bit if you end up with some funny stuff happening, like seeing both versions of the dragon or the player. Just make sure you get on the vehicle AFTER setting its new location, and getting OFF before moving it away. And you would not be able to transfer to other maps while on the vehicle - movement is restricted to just the one map.
