Why would a player-owned horse walk back to its spawn point?

[Vaz2008]

In-game I used SetOwnership on the Dapple Grey Horse from Slof's Horses. Not satisfied with just that, I opened Slof's ESP in the CS and edited the Dapple Grey Horse in these ways:

 

- Removed it from the Prey faction and added it to the HorsePC faction.

- Made it essential.

- Changed its energy level to 25 to match the other player horses.

- Changed its responsibility to 0. I don't want my own horse telepathically reporting my crimes. o_O

- Gave it reins, a bridle, and a saddle.

- Removed its original AI packages and, at first, replaced them with HorsePCGoHome, HorsePCStandStill, and HorsePCStay.

- Did not assign a script to it. I can only vaguely understand the scripts that are assigned to the other player horses, but it doesn't look like they include any functions relevant to a horse that isn't bought from a stable.

 

I saved the ESP, rebuilt my bashed patch, and loaded the save I had made when I was mounted on the horse some distance from Anvil. It was now wearing tack, so I felt that I had succeeded...except, when I dismounted, the horse immediately began walking away. It walked all the way back to a spot near the Anvil stable. Slof placed this particular horse inside the corral there, hence this thread's title.

 

Reopened the ESP in the CS and removed the HorsePCGoHome package from the Dapple Grey Horse.

Saved ESP, rebuilt bashed patch, loaded game.

Dismounted Dapple Grey Horse.

It walked away toward Anvil again.

 

Reopened the ESP in the CS and removed the HorsePCStandStill and HorsePCStay packages from the Dapple Grey Horse.

Instead, I gave it aaaDefaultStayAtCurrentLocation.

Saved ESP, rebuilt bashed patch, loaded game.

Dismounted Dapple Grey Horse.

It walked away toward Anvil again. To confirm my suspicion about its destination, I followed it all the way to the corral.

 

...Why. :[

[Vaz2008]

Apparently there was indeed something in those scripts that was needed, or maybe it was the HorsePC<City>GoHome package.

I gave the Dapple Grey Horse all the AI packages that HorsePCWhiteAnvil has (after removing aaaDefaultStayAtCurrentLocation) and also gave it a trimmed version of HorsePCWhiteAnvilScript (deleted the Begin OnDeath section because this horse, being essential, is not going to die).

That solved the problem.