Throwing an ender pearl through a nether portal behaves differently depending on whether it is thrown from the overworld to the nether or from the nether to the overworld.

What I expected to happen

I expected to be teleported after following the pearl through the portal.

What actually happened

I was teleported after throwing an pearl and then entering the nether, but was not teleported after throwing a pearl and leaving the nether. It seems that the pearl is correctly transported one way, but not the other.

Steps to reproduce:
You need multiple nether portals behind each other, which can be created using

1. /fill ~1 ~ ~1 ~11 ~4 ~4 obsidian
   

2. /fill ~1 ~1 ~2 ~11 ~3 ~3 air
   

3. /fill ~1 ~1 ~2 ~11 ~1 ~2 fire
   

If you do that in the Overworld nothing happens until you enter the Nether, however when you do it in the Nether it teleports you where you would end up in the Overworld, for example 10000 becomes 80000 (times 8).

Suggested solutions

1) Have throwing a pearl from the nether to the overworld teleport the player after following the pearl through the portal.

2) Have the pearl become 'lost' (i.e. have no effect) regardless of the direction it is thrown. (Less desirable solution than option 1).

3) Have pearls not be affected by portals and continue in the same dimension (as if the portal wasn't there).

Untested related behaviour

I've not tested ender pearls with end portals. Perhaps check this too...