What happens when you get enlarged while mounted?

[kuey]

As title. The image suddenly got stuck in my head. What happens if you riding a horse, and someone cast enlarge on you. By RAW, you can no longer stay mounted since the horse is no longer one size larger. And RAW, you can occupy the same space. So do you pop over to an adjacent space? But normally, you need an action to dismount, but what if you have no actions (either 'cos you were enlarged outside your turn, or you cast it on yourself and have no actions left)?

[shroudb]

While not a hard rule, this is the suggestion given in the mounted combat section for getting dismounted (in the example's case by the death of the mount, but it can work for multiple reasons).

Quote:

but if they were in motion, you should probably have the rider attempt a Reflex save. If they fail, the rider is thrown a short distance and falls prone. Setting a simple expert DC of 20 often works well for such checks.

[Ravingdork]

I'd just have the giant Stand as part of the enlarge effect. Their legs get longer as they get taller until their feet touch the ground and are able to support their own weight instead of the the mount.

They would in effect no longer be mounted. I'd consider shunting one or the other to a new space as well, if one is available, since two Large creatures can't occupy the same space.